shall not be allowed to be in the space between the fixed
and traversing portions of a self-acting machine, unless the
machine is stopped with the traversing portion on the outward
run, but for the purpose of this provision the space in front
of a self-acting machine shall not be included in the space
aforesaid.”
Factory Act, 1901, Sec. 156.--“The expression ‘machinery’ shall
include any driving ‘strap or band,’ which are therefore subject
to the same provisions as to safety as mill-gearing and machine
tools.”
The Acts also give powers to deal with dangerous machinery or parts
thereof:--
Factory Act, 1901, Sec. 17 (1).--“By application to a Court
of Summary Jurisdiction for an order prohibiting the use of a
machine dangerous to life or limb until it is duly repaired or
altered.”
Factory Act, 1901, Sec. 13 (2).--“By notifying it as dangerous,
in which case it becomes illegal for young persons to clean such
parts in motion.”
_Fencing of Dangerous Machinery._--With respect to the fencing
of machinery in a factory, the importance of the words “all dangerous
parts of the machinery,” which were superadded by Sect. 6 (2) of
the Factory Act of 1891 to Sect. 5 (3) of the Act of 1878, should
be carefully noted. Formerly there was absolute obligation to fence
only in respect of prime movers and mill-gearing, whilst in the case
of other machinery which an inspector considered dangerous, he was
required by Sect. 6 of the 1878 Act to serve notice to fence on an
occupier, who was empowered, if he thought fit, to have the matter
determined by arbitration. Now the obligation to fence extends to
all dangerous parts of the machinery, and the question whether it
is dangerous or not has to be decided by the Court in each case. In
connection with this it should be noticed that in the case of Hindle v.
Birtwistle (1897) the Court of Queen’s Bench held that the enactment
applies to all machinery from which, in the ordinary course of working,
danger may arise by reason of carelessness on the part of the workmen,
or of external causes. It should therefore be sufficient, in order to
prove the dangerous character of any part of a machine, to show that
accidents are frequently caused thereby.
In propounding certain rules for safety, which should be carefully
carried out in the construction of all machines, it may be pointed out
that these are not based upon mere opinion, but on the experience and
statistics of many years.
_Set-screws._--It has been one of the most pernicious habits of
almost all machine makers in this country to send out their machinery
bristling with projecting set-screws, etc., which are not only
unsightly, but also the frequent source of accidents through catching
clothing. They are often situated either on or in close proximity
to shafts, spindles, collars, or cog-wheels, whereby the dangers
attendant on these are greatly enhanced. Hence our first rule, which
should be absolute respecting all machinery, should be: (1) _No
projections shall be allowed on anything that revolves._ There are
various methods of avoiding such projections by countersinking or
otherwise, of which illustrations are given above (Figs. 7 to 9).
[Illustration: FIG. 7.--Shows a safe form of
set-screw (_s_), which is deeply recessed, and can only
be adjusted by a box key (_k_).]
[Illustration: FIG. 8.--For use with screwdriver.]
[Illustration: FIG. 9.--Halstead’s Patent
Unbreakable Square-hole Solid-ended Grub Screw. For use with
square-ended key, similar to railway carriage key.]
[Illustration: FIG. 10.--Incomplete guards for
spur wheels. (The points of danger are marked A, A and B, B
respectively.)]
[Illustration: FIG. 11.--Spur wheels with suitable
guards (G, G). (The arms of wheels may be covered with discs
if needed).]
_Toothed Wheels._--Toothed wheels are probably the cause of more
accidents than any other portion of a machine, and their protection
has been and is still sadly neglected. They are frequently sent out
by makers either with no guard whatever, or with such an inefficient
guard as only to partially cover the wheels, thereby doubling the
danger to be met by forming two points of junction between the wheels
and the guard instead of one only presented by the wheels themselves
(Figs. 10 to 12). Our second rule should therefore be: (2) _All
toothed wheels shall be so effectually covered as to leave no danger
between the guard and the wheels._
[Illustration: FIG. 12.--Shows a good form of guard
(D, D) to cover bevel wheels (E, E).]
_Shaft or Spindle Ends._--Machine makers frequently leave
projecting shafts or spindles at each side of a machine so as to allow
of choice in the arrangement of pulleys. These are frequently a source
of serious accidents, and our third rule should be: (3) _All exposed
shaft ends shall be securely covered._ This can easily and simply
be done by means of a metal cap fitting sufficiently close to revolve
with the shaft, but which will instantly stop on clothing, etc., being
caught by it (Fig. 13).
[Illustration: FIG. 13.--Shows a method of covering
shaft ends with a sheet-metal cap (G).]
_Loose Pulleys and Strap Forks._--Most machines are now supplied
by makers with loose pulleys and strap forks, but exceptions can be
found, more especially in the manufacture of cotton, in the case of
carding engines and drawing frames; on the former, though loose pulleys
are invariably supplied, strap forks are in most instances absent,
thus necessitating the moving of the belt from one pulley to the other
by hand or by a stick, a very dangerous proceeding, causing frequent
accidents. The most dangerous point is where the belt first touches the
driving pulley, and this is guarded where a well-arranged strap fork
is provided. In the case of drawing frames both loose pulley and strap
fork have generally been omitted, with the result that the undershaft
cannot be stopped for cleaning without throwing the belt off by hand,
causing additional danger in replacing the belt on the pulley. Our
fourth rule, therefore, should be: (4) _Loose pulleys and strap forks
shall be provided for all machines._
_Plate Wheels._--Arm wheels running at high speed are frequently
the cause of accidents. Such are specially found in the balance wheels
of power looms, the rim pulleys of self-acting mules, and the speed
wheels of platen printing machines. These wheels can in almost all
cases be made safe, and our last rule should be: (5) _Plate wheels
or wheels filled in shall be substituted, wherever possible, for arm
wheels running at high speed_ (Fig. 22).
Each of these rules relate to intrinsic parts of the machines, and
should therefore be dealt with by the makers themselves, who can
carry them out with little or no extra cost at the time of making.
Unfortunately, however, it has been in many instances the practice to
have one type of machine for the home, and another for the foreign
market, the latter with much more efficient guards, owing to the
stricter laws which prevail in certain countries as to the occurrence
of accidents.
_Hoists._--We now come to the last head of our subject, viz., the
safe-guarding of hoists and other lifting tackle. The requirements of
the Factory Act as to these are absolute.
Factory Act, 1901, Sec. 10 (_a_).--“Every hoist or teagle
shall be securely fenced.”
The importance of this enactment may be gathered from the fact that in
1899 there occurred 27 fatal and 315 non-fatal accidents from hoists
alone, whilst other lifting tackle was responsible for 66 fatal and
1497 non-fatal. Parliament has fully recognised the dangers arising
from this class of machinery by the omission, in the Factory Act of
1891, of the limitation contained in the Act of 1878, “near to which
any person is liable to pass or be employed,” thus placing hoists on
precisely the same footing as prime movers, the fencing of which, as
shown above, is absolutely compulsory.
[Illustration: FIG. 14.--Knowles’ Improved Safety
Hoist.]
Cage hoists are most frequently found in factories, and in these the
cage should invariably be roofed over, whilst each side of the cage
should be cased in, except that used for exit, thus avoiding danger
from anything falling down the hoist-way, and also from projecting
obstacles therein. On each floor the hoist-way should be guarded by
doors not less than 5½ to 6 feet in height. The single bar or chain
which used so frequently to be found is a constant source of danger
from persons looking down the well and being trapped between the bar
and the bottom of the cage. Falls down the hoist-way through absence
of any protecting gate, through the latter being carelessly left open,
or owing to the cage being moved to another floor without warning,
frequently occur. For perfect safety hoists should be in the sole
charge of a special attendant, whose duty it should be to travel with
the cage, opening or shutting the doors at each landing as required,
the fastenings of which should be accessible only from the inside.
Otherwise, automatic gates may be used, so adjusted as to open on the
arrival at, and close on the departure of the cage from, each landing;
it should not be practicable to open these from the outside, and where
there is not sufficient headway for a gate six feet in height, it may
be made to telescope.
There are several patent hoists which answer to this description
in greater or less degree, but we must content ourselves here with
an illustration and description of one of the best methods of
safe-guarding hoists, viz., by means of the Knowles safety locking gear
for cage hoists (Fig. 14).
Careful attention should be paid to the gear for suspending the cage,
in order to prevent accidents from the breaking of the ropes and the
precipitation of the cage to the bottom of the hoist-way. For greater
safety two wire ropes should be used, which should be periodically
and systematically examined. Some one of the various safety gears
for arresting the fall of the cage should also be adopted; in this
connection we give an illustration (Fig. 15) of “Morgan’s patent safety
catches,” which sustain the cage in case of the hoisting ropes breaking
through some mishap. In the matter of safe-guarding hoists, also, we
are far behind other countries where the law compels employers to
provide safety catches and doors for every cage hoist.
_Teagles._--Hoisting of goods is often performed by means of a
teagle either outside the buildings of the factory, or inside through
openings in the floors. In the latter case these openings in each floor
should be securely railed; whilst in the former the attendant should
invariably be supplied with a safety belt, strong enough to suspend
him in the air should he fall. In case, however, of an outside teagle,
the dangerous and laborious work of swinging the goods into the room
can be avoided by the use of a self-landing and delivering hoist (Fig.
16), which will not only lift goods off the lorry and take them into
the room, but will also pick them up inside the room, travel with them
outside the doorway, and lower them on to the lorry.
[Illustration: FIG. 15.--Morgan’s Patent Safety
Catch.]
_Cranes, Winches, etc._--Although the Factory Acts deal
specifically only with “hoists” and “teagles,” yet the numerous
accidents mentioned above as attributable to other lifting tackle,
plainly point to the urgent need for safeguards, and care in its use.
The provisions of the Acts as to hoists are of long standing, and were
enacted when the term “factory” did not embrace every dock, wharf,
quay, warehouse, and building in course of erection. Great care,
however, should be taken to securely fence all bevel wheels of cranes,
winches, etc., and periodical examination of all chains, ropes, etc.,
should be strictly carried out. It should be remembered that steam
cranes partake of the nature of the two first divisions of our subject,
viz., engines and mill-gearing.
[Illustration: FIG. 16.--Wadsworth’s Self-Landing
and Delivering Hoist.]
[Illustration: FIG. 17.--Self-acting Mules. Guards
for the drawing-out band, and pulley at the out end of frame.
Shows unsatisfactory guard (A).]
[Illustration: FIG. 18.--Shows a guard which
completely covers the band round pulley (C, D).]
In the preceding pages some pains have been taken to set forth certain
regulations which should equally apply to all machinery. It has been
shown that the provisions of the law as to fencing prime movers and
hoists are absolute, and equally so those applying to mill-gearing
unless it be in such a position and of such construction as to be
equally safe, as if it were fenced, whilst the machines by which the
manufacturing processes are carried out are dealt with by means of the
general instruction that “all dangerous parts of the machinery shall be
securely fenced,” subject to the same reservation as to position and
construction as in the case of mill-gearing. Except in the instances
of grinding in tenement factories, chaff-cutting machines, and perhaps
it may be added, of self-acting machines, the law has not yet entered
into any details as to safe-guarding machine tools. Apart, however,
from general rules applicable to all, there remain certain machine
tools which, owing to the nature of their construction and use, are
peculiarly liable to the occurrence of accidents. For these special
guards are necessary, and their invention and use have been spurred on
by the liabilities of employers under the Compensation Acts. It would
not be possible here to illustrate a tithe of these machines and the
most approved guards invented for them, but it is proposed to select
a few machines which are shown by statistics to be the most frequent
cause of accidents, and the means by which these accidents may, in part
at any rate, be obviated.
[Illustration: FIG. 19.--Self-acting Mules.
Elevation--Foot-guard for carriage wheels. The guard (G) is
fixed to the bracket (B), and surrounds the wheel (W) at a
slight distance above the slip or rail (S).]
_Self-acting Mules._--Dealing first with our great textile
industries, and specially with that of cotton, it will be found that by
far the greatest number of accidents occurs in the mule-rooms. Owing to
the complicated nature of their construction no one illustration could
exhibit all the necessary guards for self-acting mules, but an analysis
of the accidents caused by them shows that the parts which are the most
fruitful source of injuries to workers are:--
1. Scroll or draw bands and pulleys.
2. Carriage wheels and slips.
For the first, incomplete and approved guards are shown in Figs. 17
and 18; whilst for the second, two types of guards in common use are
illustrated in Figs. 19 to 21.
[Illustration: FIG. 20.--Hargreave’s Mule Carriage
Wheel Guard.]
[Illustration: FIG. 21.--Hargreave’s Mule Carriage
Wheel Guard.]
_Looms._--Next to mules, power looms are the most frequent cause
of accidents in a cotton mill. These present an excellent specimen of
the dangerous character of exposed arm wheels running at high speed
alluded to above. An illustration of safeguards for the ends of looms
will be found in Fig. 22. During 1899 flying shuttles were the cause
of 1 fatal and 161 non-fatal accidents. Shuttle guards, of which an
example is given in Fig. 23, are either rigid or semi-automatic, but
in either case great care has to be taken that they are not fixed too
high on the slay cap.
[Illustration: FIG. 22.
FRONT
Balance Wheel removed, showing guard
over spur wheels.
SIDE
Spur Wheels guarded
at intake side.
FRONT
Balance Wheel (Plate Wheel) in position, guarding
the crank and tappet wheels (toothed).]
[Illustration: FIG. 23]
Turning to non-textile machinery, probably no three classes of machine
tools show so large an array of accidents as:--
1. Circular saws.
2. Planing machines.
3. Power presses.
Each of these classes present dangers peculiar to itself, and therefore
needs special safeguards.
[Illustration: FIG. 24.--Elvatka Guard.]
_Circular Saws._--Circular saws during the year 1899 were
responsible for 1289 accidents, of which 9 proved fatal. The purposes
for which they are used are so various that no one universal guard
is practicable, but in all cases a riving knife should be provided
at the back of the saw, whilst as much of the top and front should
also be covered as circumstances will permit. Figures 24 to 27 show
illustrations of a few guards which appear best to fulfil these
requirements.
[Illustration: FIG. 25.--Longmore’s Guard.]
[Illustration: FIG. 26.--Victor Guard.]
[Illustration: FIG. 28.--Campbell and Greenwood’s
Guard.]
_Planing Machines._--Accidents through planing machines are of
frequent occurrence. They are often of such a severe nature that no
planing machine should be permitted to be used without an efficient
guard, of which an illustration is given in Fig. 28.
[Illustration: FIG. 27.--Woodhouse and Mitchell’s
Guard.]
_Power Presses._ Power presses like circular saws are put to so
many uses that various forms of guards are needed to suit the variety
of work. They are usually put into motion in one of two ways: either
the plunger is released by means of a foot treadle or by a hand lever.
Of these the latter naturally presents the fewest elements of danger,
owing to the necessary position of one hand whilst using the lever.
Additional safety has recently been imparted by the introduction of
machines furnished not only with hand levers, but also fitted with
slides obviating any necessity for either hand to approach the die.
Fig. 29 illustrates an approved guard for an ordinary tin stamping or
cutting press.
[Illustration: FIG. 29.--Power Presses.]
ADDENDA.
FIG. 14.--DESCRIPTION OF KNOWLES’S IMPROVED SAFETY
HOIST.
The rod A, which extends the full depth of the hoist well, is
attached at its upper end to the lever B, the latter carrying
the lever C with the stop or projection D, which drops into
the toothed rim S on the side of the starting pulley E, and
locks the hoist when a door is open, as in Fig. 1. Each door
is provided with the lever H, mounted on the centre I, one end
being coupled to the rod A by the arm K and rod L, the other
end being fitted with the bolt or draw-bar X. To the lever C is
attached the hook T extending over the lever B, by which the
stop or projection D, on the lever C, is lifted out of gear with
the tooth rim S in making an upward movement, caused by dropping
the bolt or draw-bar X. When the lever B drops, by the action
of opening one of the doors, the stop or projection D on the C
is pressed or forced into the toothed rim S by the spring V, as
shown in Fig. 2. This apparatus operates as follows:--When the
attendant desires to work the hoist, he simply closes the door
and drops the bolt or draw-bar X into the hole or slot N in
the threshold O, which lifts the levers B and C by the upward
movement of the rod A, and moves the stop or projection D from
the toothed rim S, as in Fig. 3, at which point it remains
until one of the levers H is operated from the inside by the
attendant, when it is locked, as shown in Fig. 2. When the stop
or projection D is removed from the toothed rim S, the starting
band or chain P is at liberty to be operated in the requisite
direction at will. To prevent the hoist being started when a
door is open, the lever H is latched into the catch or fixing R.
It is impossible to start the hoist until the attendant has both
closed and bolted the doors.
FIG. 15.--MORGAN’S PATENT SAFETY CATCH. (An improved
safety gear for colliery cages, hoists, lifts, etc.)
_To sustain the Cage, in case through any mishap the Hoisting
Ropes break._--In the arrangements of these catches, two strong
steel colliery rods are stretched from top to bottom of the
hoist well, and the cage is fitted with two or more cams, across
the face of which grooves are made to correspond with the
strands of the steel guides.
The cams are fitted in a steel casing, through which the guides
pass, so that should the hoisting ropes break, the steel guides
are at once gripped by the cams, which hold the cage suspended.
H. S. RICHMOND.
CHAPTER XV
AGRICULTURE; HORSES; CATTLE
_Agriculture_
(1) _Labourers._--The manifold occupations included under the
general term of tilling the soil, exercises a beneficial effect on
the husbandman as regards mere length of days, for he often lives far
beyond the allotted span, although he rarely comes to the end of his
career a hale and hearty old man. His operations are carried out for
the most part in the open air, leisurely, and in a greater or less
degree of isolation. His condition, therefore, has its drawbacks as
well as its advantages. As one of the oldest occupations of mankind
it has been very largely adopted as a means of gaining a livelihood,
and, until recently, the supply of farm labourers has exceeded the
demand. It is badly paid; the farmer, at least in England, has many
anxieties, disappointments and losses in his crops and stock; the
labourer receives but small wages, and has perforce to put up with
scanty living and poor accommodation. The living is made worse by the
ignorance of cooking and domestic economy, which is so general amongst
the wives and daughters of the labouring class. Field work begins early
in the morning, and leads to exposure in all weathers. It is usually so
monotonous, that it is unattractive to the better intellects amongst
the lower orders; it is sometimes very hard, as during hay-making and
harvest, and it is occasionally dangerous, as in hedging and ditching.
“Rheumatic” affections are foremost amongst the bodily ills of field
workers, not often as acute rheumatism, but rather in some of the
protean forms which affect the connective tissues. Osteo-arthritis,
sciatica, lumbago, and valvular heart lesions are commonly met with.
Indeed, the rheumatic affections of old age have been known for so
long a time that Scapula, in his great lexicon, says, with doubtful,
though picturesque, etymology, “Γέρων, the Greek word for an old
man, has been derived by some παρὰ τὸ εἰς γῆν ὁρᾷν, because old men
by their stooping look towards the earth; though others, with more
probability, derive it from the same stem as Γέρας, on account of the
reverence due to age.” The etymology, whether right or wrong, draws
attention to the stooping habit which is typically a senile kyphosis,
though it is accentuated by occupation, and is found early in middle
life in agricultural labourers, as often as in tailors, cobblers,
clerks, Swiss mountain porters, and, latterly, in some bicyclists. True
senile kyphosis or stooping arises from simple weakness and wasting
of the tissues, with absorption of the intervertebral discs, and is
not necessarily due to rheumatism. But amongst agricultural labourers,
it is usually associated with osteoarthritic changes, which tend to
unite the individual vertebræ by bridges of bone, whilst it thickens
the spines and hardens the ligaments. The stage of anchylosis is often
preceded by a period of inflammatory softening, which leads to more or
less deformity of the vertebral column, for lateral curvature is nearly
as common as the forward stoop to which the name kyphosis is given.
The same factors of hard manual labour, often in constrained attitudes
and under unfavourable conditions of weather, produce other “rheumatic”
affections, such as pains in the limbs, aching in the bones and
stiffness in the joints, which disturb the comfort without lessening
materially the wage-earning power of the rural population. No one can
have attended the local fair or feast without noticing the peculiar
shuffling walk, and the knock-knee of the ploughboy, the results
respectively of flatfoot and over-growth, aided by badly fitting,
uncouth boots, and a habit of walking over uneven surfaces.
The palmar fascia of the hand often becomes contracted--Dupuytren’s
contraction--a condition whose cause is unknown, though it has
been variously attributed to such predisposing causes as gout and
rheumatism, or to habits and occupations necessitating pressure in
the palm and flexion of the fingers, as in digging. The contraction
usually begins in that portion of the fascia which is continued on
to the sheath of the flexor tendon of the little finger, afterwards
attacking the portion extending to the ring finger, and sometimes
the remaining fingers. The fingers are thereby flexed and drawn down
towards the palm, with which they may even be fixed in contact. This
form of contraction may be distinguished from that due to a contracted
tendon, by the puckering of the skin in consequence of its adhesion
to the fascia, and by the contracting band bifurcating to be inserted
upon either side of the flexor tendon, whilst the contracted tendon is
placed centrally, and can be traced under the annular ligament.
The kindness of the late Dr Tinley, and Dr Granger at Whitby, and of
my brother-in-law Mr G. H. Fosbroke, the County Medical Officer of
Worcestershire, has lately allowed me to examine the death returns
of two typically rural districts. The chief causes of death are
bronchitis, including pneumonia and pleurisy; heart disease, a very
vague term covering a multitude of pathological conditions; and
phthisis. The deaths from bronchitis and heart disease, in a period of
ten years, are nearly equal in number, whilst those from phthisis were
only half as many as either of the other two.
Typhoid fever is endemic in many districts, owing to the improper
disposal of excrement, and from the use of polluted water in surface
wells.
Some of the older countrymen living in the fen districts east of
Cambridge still take opium regularly to keep off ague, and I have a
working hypothesis that these same dwellers in districts which were
once highly malarious are now more subject to cancer than persons who
live in towns where the soil is drier and insects are fewer. Be this
as it may, however, gardeners and those who have to handle soot in the
course of their work are liable to develop epitheliomatous ulcers of
the hand and wrist more often than those who are free from such source
of local irritation.
Lunacy is increasing markedly amongst the rural population in some
parts of the country, and notably in Ireland. This is probably due
to the tide of emigration carrying away the more highly endowed and
enterprising, whilst it leaves the old and those who are enfeebled in
body and mind.
Agricultural labourers do not, on the whole, fare very badly. Even with
low wages and bad sanitary surroundings, the social condition of the
English farm hand compares most favourably with that of the peasantry
in many European countries. The absence of the three great diseases
epidemic amongst those who are reduced to the lowest depths of misery
by chronic starvation, is a proof of this superior position. The three
diseases are ergotism from the use of spurred rye; pellagra due to bad
maize; and lathyrism caused by the consumption of the chick-pea.
Ergotism is rife amongst the rye-eating inhabitants of Germany,
Bohemia, Sweden, Russia, and the central provinces of France. It occurs
especially after rainy seasons, and the bread made from the diseased
rye is violet in colour, and of a disagreeable taste and smell. It is
usually badly made and badly baked. The symptoms of ergot poisoning
are either acute or chronic. The acute form begins with giddiness,
headache, lassitude, and disturbances of sight and hearing, which have
led to its being called “ergot intoxication.” The chronic poisoning is
ushered in with symptoms of ergot intoxication, but the later stages
are either convulsive or gangrenous. The convulsive form is marked by
intermittent clonic spasms of the limbs, with dilatation of the pupil,
delirium, and coma, which soon ends in death, without any appearance
of gangrene. The mortification in the gangrenous form is preceded by
pain in the part, with intolerable “creeping” feelings, followed by
diminished sensibility, which ends in dry gangrene, and finally in
separation of the affected tissues. The patients suffer occasionally
from vomiting of blood, or from passing blood in the urine, the
bleeding being as difficult to arrest as in hæmophilia.
Pellagra from the consumption of bad maize, truly known as the
_malattia della miseria_, is epidemic in parts of France, Spain,
Italy, Africa, and Brazil. It requires for its full manifestation
a most wretched peasantry. Pellagra is characterised by headache,
depression of spirits, sleeplessness, cramps, palsies, giddiness, and
dyspepsia. There are vague but often severe pains in the spine and
joints, and there is a skin eruption, which begins in April or May,
and goes from bad to worse, until it begins to improve in July or
August. The eruption is an erythema of the parts exposed to the sun.
The skin becomes swollen and tense, with petechiæ and bullæ, which
leave indolent ulcers when they break. The attacks recur in the spring
of each year, until in time the skin becomes thickened and of a light
sepia colour. The nervous symptoms culminate in a settled melancholia.
The spinal cord appears to be definitely affected both in ergotism and
pellagra, the posterior columns suffering chiefly in ergot poisoning,
the lateral columns in pellagra.
Lathyrism results from the use of the chick-pea (_Lathyrus
sativus_, _cicer_, or _clymenum_) as an article of diet.
Like ergotism and pellagra, it is associated with extremely wretched
conditions of life, and has been observed in France, in the Abruzzi,
at Allahabad, and in other parts of India. Oxen, horses, pigs, and
geese are attacked as well as men. The symptoms point to an affection
of the lower part of the spinal cord, and are manifested by a sudden
inability to use the legs in the ordinary manner. The legs are so
stiff that when the patient walks he is obliged to throw his body into
a succession of curves, so that he describes a screw or figure of eight
as he proceeds. There is much hyperæsthesia of the lower extremities,
which may be followed by loss of sensation, though the patient
complains of the same tingling sensations as are felt in ergotism. The
onset is usually sudden, and is coincident with the advent of cold
weather, but the symptoms take four or five weeks to reach a maximum.
The increasing use of machinery in ploughing, reaping, threshing, and
other farming operations leads necessarily to a greater number of
machine accidents than was formerly the case when labour was abundant
and machines were few. Even small farmers now possess a chaff-cutter,
and injuries to the hands and arms produced by its cog-wheels are
correspondingly frequent. Much more serious injuries are caused by
the large threshing and reaping machines, which are sometimes tended
by unskilled persons, as they are often let out on hire. Overstrain
from the lifting of loads in awkward positions during harvest is no
uncommon cause of hernia in those who are otherwise predisposed to this
condition. Poisoned wounds of the hand, and penetrating wounds of the
eye, are often sustained in the occupation of hedging and ditching, a
form of labour which is also the cause of rheumatism. Occasionally,
too, an agricultural labourer presents himself with a viper bite, for
vipers are still indigenous in several parts of England. He complains
of a burning pain at the part bitten, the limb swells and becomes
discoloured within an hour or two, there is great prostration marked
by sweating, vomiting, feeble pulse, and restlessness. The more acute
symptoms usually pass off in the course of twelve to twenty-four
hours, but in unhealthy persons the swelling increases; there may be
suppuration, and the bite then ends in a severe attack of inflammation
of the tissues, known as cellulitis.
In like manner stings from bees, wasps, hornets, and gnats, which
are usually of small importance, may become serious, either from the
bad condition of the patient’s health, or from the position of the
sting, as when the mouth or conjunctiva is affected. A tolerance is
established for bee-stings and gnat-bites, as is shown by the very
slight reaction which takes place in bee-keepers and the inhabitants of
mosquito countries, as compared with the sufferings of a town-bred man
who is stung by either of these insects.
In mushroom-poisoning the poisonous constituent is muscarin, a
nitrogenous body allied to cholin. It causes vomiting, diarrhœa,
and prostration, with convulsions and contraction of the pupil.
Death may occur from syncope and failure of respiration, but such an
ending is rare, except in children, because the vomiting promotes the
evacuation of the poison. Atropin is the physiological antidote, and
a subcutaneous injection of as much as ¹⁄₃₀ to ¹⁄₁₆ of a grain may be
given hypodermically, whilst diffusible stimulants are administered by
the mouth.
(2) _Gardeners_ appear to suffer from many of the affections
common to farm-labourers, except that as they receive higher wages
they are better clothed, better fed, and better housed, and are thus
able to withstand climatic changes more successfully. It is said, on
the other hand, that gardeners are somewhat more liable to phthisis.
Their work in hothouses causes them to catch cold more easily, and may
thus increase any predisposition to infection by the tubercle bacillus.
The handling of such plants as the _Primula obconica_ sometimes
produces a very troublesome erythema of the skin, whilst constant
contact with fresh soil allows greater opportunities of contracting
tetanus.
The Museum of St Bartholomew’s Hospital contains an interesting
specimen, showing that the epitheliomatous form of cancer sometimes
follows the irritation produced by gardening. The specimen consists
of the hand and part of the forearm removed on account of a growth
covering nearly half the surface of the skin. The growth is warty, very
vascular, superficially ulcerated, and with an everted sinuous edge.
It bears a close resemblance to an ulcerated cancer of the scrotum in
chimney sweepers. The patient was forty-nine years old. Five years
before the amputation of his hand he was employed as a gardener in
strewing soot over the ground for several mornings in succession;
a warty growth then formed, and it increased and ulcerated in the
spring of both the following years, whilst he was similarly employed.
After this, though he was no longer in contact with soot, the disease
increased until the limb was removed. He recovered completely after the
operation. The case is related by Sir James Earle in his edition of
Percivall Pott’s works.
Dupuytren’s contraction of the palmar fascia is by no means uncommon
in gouty and rheumatic gardeners as they become advanced in years. It
is best treated by dissecting out the contracted bands, if this can
be done without suppuration, the resulting scar being afterwards kept
supple by daily massage.
_Horses._
(3) _Ostlers, Stablemen, and Cartmen._--This class of men, from
their close attendance in stables, necessarily contract the diseases
which are transmissible from horses to ourselves. Foremost amongst
these diseases are glanders and farcy, of which I have seen several
cases in veterinary students; and tetanus, whose bacillus is said to
live in the horse’s intestines.
Glanders, in its acute or generalised pyæmic form known as farcy,
attacks grooms, ostlers, coachmen, knackers, and veterinary surgeons,
because they are brought into contact with diseased animals. It has
also been seen as a result of accidental infection in the pathological
laboratory during the preparation of mallein; in surgeons who have
operated upon glandered patients, and even in washerwomen who have
washed the clothes of those affected.
Glanders occurs in an acute form which kills in eight to fifteen days,
and a chronic form said to last as long as eleven years.
Acute glanders in man has an incubation period of three to eight days,
though the symptoms are occasionally delayed for three weeks, or they
may appear within twenty-four hours, and suppuration may occur at the
end of the second day. The patient complains of a general feeling of
ill-health with headache, and such vague pains in the muscles and
joints as lead him to think that he is about to have acute rheumatism.
The symptoms increase in severity, and there is often sufficient
gastro-intestinal disturbance associated with deafness and stupor to
lead to an erroneous diagnosis of typhoid fever. The pulse is full and
soft, beating 90 to 100 in a minute; the skin is dry; the mouth foul,
and epistaxis is frequent. Swellings--“the farcy buds”--soon appear in
the intermuscular planes near the joints on both sides of the body. The
swellings are at first hard, but they quickly soften, point, burst, and
leave large foul ulcers, which eventually contract into sinuses if the
patient survive. The case may then be looked upon as one of chronic
pyæmia, especially as rigors are numerous and severe, but all doubt as
to the true nature of the disease is set at rest when the face becomes
affected. The skin over the nose is reddened and swollen, whilst the
mucous membrane is injected and discharges a fœtid secretion, clear
at first, but soon becoming yellow, purulent, viscid, and finally
blood-stained. Ulceration of the nasal mucous membrane occurs less
frequently in man than in the horse. The conjunctivæ are often affected
in a manner similar to the nasal mucous membrane, and the inflammatory
condition spreads to the pharynx, palate, and glottis. Dyspnœa, with
pleuritic pain, may be a marked symptom of the disease, extensive
gangrene may occur, and death follows.
Glanders is generally inoculated through a wound or abrasion, but
the bacilli are able to penetrate to the uninjured lymphatics of the
skin by way of the hair follicles, and in the case of two veterinary
students who have been under my care the infection was directly
traceable to their being sneezed over by a glandered horse they were
examining. If a wound be the seat of infection it may heal, but in a
day or two it becomes swollen and painful, an eruption of vesicles
often appears round it, and the lymphatics become swollen and painful,
though the glands are rarely affected. The skin, in some cases of
farcy, shows erythematous patches like those of erysipelas or erythema
nodosum. The patches become pustular or phlyctenular, or a pustular
rash without umbilication may first be noticed. The latter form of rash
is said to be of very grave significance, for recovery seldom if ever
takes place when it makes its appearance.
Glanders affects many animals besides horses, mules, and donkeys.
It has been seen in lions, leopards, tigers, and bears in various
menageries; field-mice, guinea-pigs, and hedgehogs are highly
susceptible. Infection may result not only from direct contact with the
sick animal and its nasal discharge, but also from the pus, saliva, and
milk. Food and drink may convey bacilli directly into the alimentary
canal, which is thus affected primarily, the nasal mucous membrane
becoming involved as part of a secondary process.
Chronic glanders may last for years, the patient suffering from acute
but intermittent attacks of fever, in one of which he may die, or from
which he may wholly recover. The skin in these cases is often the part
chiefly affected. It becomes swollen and œdematous, with nodules, which
only appear in one part and break down into indolent ulcers. The ulcers
heal and leave scars which, with the destruction of the septum of the
nose and the ulceration of the pharynx and soft palate, sometimes raise
a suspicion of syphilis.
The disease depends upon the presence of the bacillus mallei and
the toxic substances produced during its growth. The bacillus may
be isolated from the abscesses, blood, enlarged skin follicles, and
the ulcers. They are more easily recognised in properly stained
“smear preparations” than in sections, and are readily cultivated
in three to five days on acid potato media at a temperature of 35°
to 37° C. as a brownish, moderately thick and opaque growth. The
active principle of the growth is “mallein,” which can be obtained
as a syrupy fluid. Mallein injected into a glandered animal produces
an inflammatory swelling at the seat of inoculation. The tumour is
tense, painful, and very extensive. The lymphatics from the seat of
inoculation to the neighbouring lymphatic glands become inflamed, and
are painful, swollen, and sinuous. The local tumour increases in size
for twenty-four to thirty-six hours, but does not suppurate unless
septic organisms have been introduced at the time of the inoculation.
It subsides slowly in eight to ten days. Inoculation is followed by
a general reaction, which appears within eight hours of the time
of injection, reaches a maximum in ten to twelve hours, and lasts
twenty-four hours. The animal shivers and sometimes has well-marked
convulsions. The test is a very valuable one for latent glanders in
horses, and as mallein diluted with ten times its volume of a ½ per
cent. solution of carbolic acid preserves its qualities unimpaired
for many months, it is now largely used in all parts of the world. A
healthy horse either does not respond at all to a much larger dose
of mallein than will affect a sick animal, or else a small swelling
appears at the seat of inoculation, which only lasts for twenty-four
hours. Glandered men, in the few cases where it has been employed, show
the same reaction to mallein as glandered horses. The Straus test is
also valuable in the diagnosis of glanders. It consists in diluting the
suspected secretion with sterile water, which is then injected into the
peritoneal cavity, and beneath the skin of male guinea-pigs. The testes
appear to swell two or three days after the injection, and the animal
dies in four to fifteen days with acute inflammation of the tunica
vaginalis, the testicles and epididymis being only rarely affected.
Acute farcy is very fatal, but 50 to 60 per cent. of the patients
affected with chronic farcy recover. The treatment at present is
most unsatisfactory. Stimulants and tonics must be given liberally.
Every abscess must be opened and disinfected as soon as possible, and
benzoate of soda may be administered in drachm doses three or four
times a day. In chronic cases marked improvement is said to have taken
place after the continued injection of mallein in doses of ¹⁄₂₀ to ¹⁄₁₅
c.c. at intervals of two or three days.
Tetanus, often called lockjaw, is due to the poison produced by
certain bacilli, which were first isolated by Kitasato, Tizzoni,
and Cattani, in 1889. The micro-organisms are delicate threads with
somewhat rounded ends, which reproduce by sporing. When the bacilli are
about to spore one end becomes enlarged, and the organism resembles a
pin or a drumstick. The spores are extremely tenacious of life, they
resist the effect of high temperatures for an unusual length of time,
they survive a temporary immersion in strong antiseptic solutions, and
they have been known to retain their vitality for more than twelve
months if they are protected from light and air. The parent bacilli are
widely distributed in garden earth, in dust, and in the excrement of
animals, especially in those of the horse, for this animal seems to be
their natural host. They have been found, therefore, in stables and in
manured fields, and they have the power of growing outside the body.
During their growth the bacilli produce a powerful poison, which
is formed so slowly that it may take two or three weeks to produce
its full effects. This poison is formed at the seat of inoculation,
for the bacilli do not seem to travel far from the place where they
are introduced, and it is generated more rapidly and abundantly in
suppurating than in aseptic wounds. It produces its effect by a
definite action upon the nervous system, and probably travels through
the circulation, though there is still some doubt whether it does not
reach the spinal cord by way of the nerves, so definite are some of
its early effects. Tetanic symptoms can be produced by the inoculation
of toxins, which have been purified of bacilli, and mice appear to be
especially susceptible to the disease thus produced.
It will be clear from what has been said that tetanus is by no means
rare. It may ensue from a wound at any part of the body, the wound
varying in severity from a total crush to a slight abrasion which
has passed unnoticed, and the case is then looked upon as one of
spontaneous origin. It is especially frequent after injuries of parts
which are usually dirty, and is consequently somewhat more common after
wounds of the hands and feet. Though gardeners, horse keepers, and
agricultural labourers often suffer, I have repeatedly seen cases in
people who have been run over, and inoculated with the foul mud of an
ill-kept London street. Horses, sheep, and cattle are also liable to
infection. But on the whole tetanus has become less frequent, since an
attempt has been made to keep wounds aseptic, or at any rate to shorten
the process of suppuration.
The onset of the disease is usually marked by a feeling of general
uneasiness and depression, unless the wound is too severe to allow
of this manifestation. The first symptoms usually consist of a
feeling of stiffness or soreness about the jaws and throat, with
some tonic contraction of the platysma-myoides, causing the _risus
sardonicus_, which is particularly well marked when the patient is
asked to protrude the tongue. Spasms of greater or less severity then
occur in the voluntary muscles, the pain varying greatly in different
patients, though it is usually less than that of ordinary cramp. The
muscles, especially those of the abdominal wall, are in a state of
persistent tension in the intervals between the attacks, the tension
being reduced to a minimum during sleep or anæsthesia produced by
artificial means. The intellect remains undisturbed unless there is
much fever. Death takes place from exhaustion as early as the third
day in acute cases, but it is often postponed for a fortnight or three
weeks.
The prognosis seems to vary with the rapidity of onset, for the
mortality is great when the incubation is under ten days, whilst nearly
half the patients recover if the symptoms do not appear for more than a
fortnight after the injury.
The treatment is largely prophylactic. A wound contracted under
suspicious circumstances, as when other cases of tetanus have occurred
in the same village or stable, should be immediately rendered aseptic
by a process of thorough cleansing. This is preferable to the use
of the actual cautery, which leads to suppuration, and thus tends
to increase the growth of the bacillus. When the initial symptoms
appear, the injured part must be removed, as the wound is a local
factory for the production of the nerve poison. Doses of antitoxin
must be administered by hypodermic injection, and I prefer to do this
by injecting it deeply into the gluteal muscles rather than into the
brain or subarachnoid space, as is now the custom. The maximum dose
of Tizzoni’s antitoxin is 40 c.c., which is equivalent to 2,500,000
units. This large dose may be given at once, 5 c.c. injections being
afterwards given two or three times a day until the tonic contraction
of the muscles has disappeared. The antitoxin appears to cure the
slighter cases, and it produces a temporary relief in the most severe,
but all the severe cases I have seen have died in spite of treatment.
Hydrophobia, the rabies of animals, is another form of poison acting
upon the spinal cord, to which huntsmen and stablemen are peculiarly
liable from the nature of their occupations. The pathology of the
disease, however, is much less clearly understood than in the case of
tetanus. Dogs, foxes, wolves, and cats; horses, cows, and deer, may
contract rabies and transmit it to man by the saliva, or more rarely by
the milk; whilst monkeys, rabbits, and guinea-pigs are susceptible to
infection. The latent period appears to vary enormously, as its limits
have been given as fourteen days to five years, though the ordinary
incubation period seems to be from three to six weeks, the length of
time depending upon the ease with which the poison reaches the nerve
sheaths, and passes along them to the nerve centres in the medulla and
upper part of the spinal cord. There is no doubt, however, that the
poison of rabies can be absorbed from the uninjured mucous membranes of
the body, especially from the conjunctivæ and the nasal mucous membrane.
In the cases which I have seen the symptoms have been preceded by two
or three days of mental agitation and apprehension without apparent
cause. Hiccough and difficulty in swallowing were the earliest signs
of the disease, and these slight symptoms of undue reflex irritability
gradually increased until the whole body became convulsed, the
patient’s sufferings being increased by the viscid saliva, which he has
attempted in vain to expectorate. Death took place suddenly either from
cardiac failure or from spasm of the glottis.
The Pasteur treatment offers the best chance of a cure to a person who
has been inoculated with rabies. Its success depends upon the fact
that the spinal cord of a rabbit dying of rabies contains the poison,
which becomes progressively less virulent after death, if the cord
be protected from decomposition by exposure to pure dry air, until
on the fifteenth day it is harmless, and a solution of the cord may
be injected into a susceptible animal without producing any effect.
Successive inoculations of an animal already infected show that it is
possible to establish a condition of complete tolerance, even for a
strong dose of the poison previously introduced, though the process
of inoculation has not been begun until five days or longer after the
bite. The Pasteur treatment at the present time consists of a series
of simple inoculations lasting fifteen days, during which emulsions
from cords of fourteen to three days’ desiccation are injected in doses
of 3 to 2 c.c. at a time under the skin of the abdomen. There is also
an “intensive” method, for more serious cases, such as the bite of
a mad wolf, or when the wounds have been on the face. In this method
the number of injections which are usually spread over five days is
compressed into three days, the whole duration of the treatment being
twenty-one days, a fresh series of injections being recommenced on the
fourteenth day. Certain modifications of Pasteur’s method have been
adopted, notably the use of an antirabic serum from the dog, prepared
by Babes of Bucharest, and an attenuated vaccine by a process of peptic
digestion, recommended by Tizzoni and Centanni.
As anthrax or charbon, sometimes known as splenic fever or malignant
pustule, is considered elsewhere in this work, it is only necessary
to state that the disease is due to the _Bacillus anthracis_,
which is readily communicated from domestic animals to man. It is met
with in the following classes: (1) those who come into contact with
living animals suffering from anthrax, as drovers, shepherds, farmers,
farriers, and veterinary surgeons; (2) those who touch the carcasses
of animals that have died of anthrax, as knackers, slaughterers, and
others; (3) those who handle the offal, skins, hoofs, horns, hair,
wools, and other derivatives from such diseased animals, as tanners,
fell-mongers, wool-workers, hair-workers, horn-workers, rag-sorters,
plasterers, furriers, felt-workers, brush-workers, mattress-makers, and
so forth; (4) in those who have a less direct connection with infective
materials; as, for instance, those who live in the neighbourhood of
such manufactories or occupations, for the disease may be carried by
animals and insects; (5) anthrax has been transmitted from person to
person by accidental contact, and may be contracted at a post-mortem
examination upon a patient or animal who has died of the disease.
There is some reason for supposing that small meat-eaters are more
susceptible to anthrax than those who are accustomed to much animal
food.
Influenza has long been known to occur in horses, and in several
epidemics the disease has been observed to spread from these animals to
their attendants. Mr Youatt first pointed out that influenza attacked
horses in very local epidemics, so that the majority of horses on
one side of a yard might be attacked, whilst there was not a single
sick horse on the other side. These prevalences and exceptions are
altogether unaccountable, but the probability of the disease is in
tenfold ratio to the number of horses inhabiting a stable. Two or three
shut up in a comparatively close stable would escape, and out of
thirty distributed through ten or fifteen little stables, not one would
be affected. But in a stable containing ten or twelve horses, although
proportionately larger and better ventilated, the disease would
assuredly appear, and when it enters one of the largest stables almost
every horse is affected. Horsekeepers may also suffer from horsepox or
“grease,” a specific eruption transmissible from the horse to man, of
which further details are given at page 246.
Much riding early in life may produce a condition of knock-knee or
bowed legs quite apart from rickets. Later in life, the tendon of the
adductor longus muscle at its point of origin below the spine of the
pubes, and more rarely the tendon of the adductor magnus, may become
partially calcified, leading to the condition known as “cavalryman’s
leg,” whilst the calcified portion is known as “rider’s bone.” A wrench
or sprain of the adductors, “rider’s sprain,” is not an uncommon
accident in the hunting-field. It leads to a very troublesome form of
chronic inflammation, which may quite prevent riding exercise, and has
proved the starting-point of a “rider’s bone.” “Rider’s bursæ” are
described as occurring in the fold of the groin and on the inner side
of the knee. They are probably enlargements of the ilio-psoas bursa or
of the bursæ situated between the semi-membranosus and semi-tendinosus
tendons, or beneath the inner head of the gastrocnemius muscle, but I
have never seen cases of either occurring in riders, though they are
common enough in tuberculous patients. Popliteal aneurism is said to be
somewhat more common in jockeys and grooms than in other persons, and
these occupations lead also to an increased liability to fractures and
dislocations.
_Cattle._
(4) _Butchers, Slaughterers, and Tanners._--Butchers and
slaughterers suffer from an undue tendency to diseases of the throat
and chest, because their occupation, at any rate in London, entails
very early rising to attend market, their shops are usually quite open,
and they are some of the few tradesmen who still cry their wares.
Their wounds are very likely to become poisoned, and as they are often
overfed and gross in habit, erysipelas is a common sequel of slight
injuries. Many porters from the Metropolitan Meat Market apply annually
at St Bartholomew’s Hospital for the relief of hernia and ruptured
muscles, which they attribute to the strains produced by carrying
heavy carcasses and to slipping on greasy pavements. The hospital
practice seems also to contain a considerable proportion of cases of
aneurism amongst the same class of men.
It is said that the habit of eating tiny bits of raw meat from the
chopping block sometimes causes butchers to become infected with
the various parasitic worms, which can be transmitted in this way.
Their meat-eating and beer-drinking habits, coupled with a sedentary
occupation, must be held accountable for their obesity and for the
frequency with which they suffer from gout.
I do not know whether tanners are liable to any special diseases except
anthrax, but in the business of leather-dressing which is carried on in
connection with tanning, the various eruptions produced by aniline dyes
are not uncommon, and there is some danger of arsenical poisoning from
the use of orpiment.
(5) _Cowmen and Dairymaids._--Cowmen and dairymaids in those
counties where they are brought into direct contact with cows
as milkmaids, are liable to several diseases by reason of their
occupations. Foremost amongst these, and of the greatest historical
interest, is vaccinia or cowpox, though it is quite a rare complaint in
English dairy farms.
Vaccinia is a specific disorder occurring in epidemics amongst bovine
animals. It is transmissible to the goat, dog, ass, camel, rabbit,
guinea-pig, monkey, and with greater difficulty to the sheep. It
is characterised in the cow by a local eruption almost exclusively
confined to the udder and teats. The eruption passes through the
successive stages of papule, vesicle, and pustule, the number of pocks
always being few, and there is considerable constitutional disturbance.
The lymph from the vesicles of a cow suffering from pox is sometimes
inoculated on the hands of the milkers, when inflamed spots appear more
particularly about the joints and tips of the fingers. The spots become
vesicular, with a swollen, hard, and inflamed base. The axillary glands
become inflamed, and the disorder is attended with some constitutional
disturbance. An analogous condition in the horse is called “grease”
or horsepox, and inoculation of the horse with cowpox will produce
“grease.” Cowpox in bovine animals and “grease” in horses can also be
produced by inoculation with human smallpox. Both “grease” and cowpox
are transmissible to man by inoculation, both diseases render him to
a certain extent immune to smallpox, and both render him less liable
to a second attack of cowpox or horsepox. It appears therefore that
smallpox, cowpox, and horsepox are very closely allied to each other.
They may be identical, the features being modified by transmission
through different animals, or they may be descended from a common
disease which was more akin to cowpox than smallpox.
Tuberculosis is so common a disease in cows that it is no wonder if
phthisis in their attendants sometimes derives its origin from a
diseased animal. The disease, however, is much more often carried by
the milk, and it is therefore a wise precaution to boil every drop
of cow’s milk for three minutes before it is given to a child or to
one who is predisposed to consumption. I have seen local tuberculosis
of the skin in one or two cases contracted by veterinary surgeons in
the course of their duties. Free excision of the affected part has
always been followed by prompt healing, and I have never known of any
generalisation.
Diphtheria is sometimes carried by milk, the infection being derived
either by accidental contamination or from the cow itself. The symptoms
of diphtheria in the cow are those of “chapped teats,” viz., rise of
temperature and an eruption on the udder and teats. The eruption begins
as vesicles, which pass rapidly into pustules, scabs, or ulcers. When
the disease is transmitted in this manner the cream and skim milk
appear to be more dangerous than the new milk, probably because the
organisms have a longer time to grow. Pigeons, turkeys, and cats have
also been credited with the power of conveying diphtheria, and in the
case of cats the accusation is proved.
There is good reason, too, for thinking that cows suffer from scarlet
fever, and that the disease is transmitted by their milk, for in no
other way is it possible to account for local epidemics of scarlet
fever which have been traced to large dairy farms.
Cows certainly suffer from ringworm, and the tinea is transferred to
those who lean their heads against them in the act of milking.
Foot and mouth disease is highly contagious amongst ruminants and pigs.
It has often been transmitted to man, usually by the milk of cows
suffering from the disease, sometimes by the butter, but most often
by direct contact with diseased beasts. Milkmaids, cowmen, shepherds,
and veterinary surgeons are thus especially liable to infection. The
disease, as it occurs in man, is ushered in by rigors, diarrhœa, and
some rise of temperature. On the second or third day a vesicular
eruption appears on the gums and tongue, and it may also occur on
the fingers or other seat of inoculation. Fortunately the disease
as it occurs in man is not serious, and recovery usually takes place
spontaneously in the course of a fortnight.
Actinomycosis.--This disease is sometimes derived by inoculation
from cattle affected with the fungus, but it comes more often from
infected grain. The symptoms are those of a chronic abscess affecting
the skin, mucous membranes, or viscera, especially the lungs, liver,
and ileo-cæcal portion of the intestine, where it is liable to be
mistaken for appendicitis. It appears on the skin in the form of
numerous globular masses, which are soft and spongy, and have an
indurated erythematous base. Pus which contains the yellow granules
characteristic of the disease exudes from the ulcerating points. The
disease runs a very chronic course, which is shortened, and the patient
cured by enormous doses of iodide of potassium. Doses of a drachm may
be given three or four times a day, and the patient not only shows no
symptoms of iodism, but improves markedly in general health.
(6) _Shepherds_ suffer by reason of their occupation in two ways.
They are of necessity closely associated with dogs, and are thus more
liable to hydatids and rabies, whilst from the sheep they obtain
flukes, and in the process of dipping they may suffer from arsenical
poisoning.
A hydatid is the asexual and cystic form of the _Tænia
echinococcus_, a small tapeworm consisting of three segments, found
in the intestines of dogs and wolves. The fertilised ova are swallowed
with impure water or with uncooked vegetables, like lettuce and
watercress, fouled by the excreta of infected dogs. The hydatid cyst
develops slowly in any part of the human body. It is most common in
the liver and intermuscular connective tissues, but it is not unusual
to find a hydatid cyst in the lungs, kidneys, pelvis, and brain, and
I have seen specimens in which the vertebræ and os innominatum were
involved. The symptoms are very obscure, and are usually dependent upon
the amount of pressure exercised by the tumour. There is sometimes a
characteristic hydatid thrill, but its absence does not invalidate the
diagnosis. For practical purposes the cyst is composed of two layers,
an external or adventitious covering formed by irritation from the
tissues of the host, and the soft and white but tough internal cyst,
filled with a limpid fluid, containing the characteristic hooklets.
The inner lining of this cyst develops daughter cysts by a process of
budding, though it is sometimes sterile.
The treatment is essentially surgical. Whenever it is possible the
tumour should be freely exposed, the fibrous cyst opened, the fluid
contents removed, and the whole endocyst withdrawn. The edges of the
ectocyst may then be sutured, and the external wound closed if union
by first intention can be practically guaranteed. But if there is any
doubt as to the probability of securing asepsis it is better to free
the edges of the outer cyst from its attachment to the surrounding
organs, and then suture it to the sides of the external opening without
including the skin. The cavity usually has to be plugged after the
removal of a hydatid from the liver.
It is not supposed that the liver fluke, or _Distoma hepaticum_,
is transmitted from the sheep to man, as is the hydatid from the
dog to the man, but it is probable that the shepherd has become
the involuntary host of the distoma in the same way as the sheep,
by drinking water containing the amphibious snail (_Limnæus
trunculatus_), which is the true intermediate host of the liver
fluke in the sheep. This trematode worm has been found in subcutaneous
abscesses more often than in the human liver. The treatment, when
possible, consists in opening the abscess and thoroughly scraping out
its contents, for they show a great tendency to refill.
_Pig-keepers._--It does not appear that pig-keepers suffer from
any particular diseases by reason of their occupation. It is possible
that where only a few animals are kept and are afterwards eaten by
the owners there may be some increased liability to trichiniasis,
which is an inflammatory state of the voluntary muscles due to the
irritation produced by the presence of the nematode worm, _Trichina
spiralis_. I recently saw a young lady who was suffering from a
chronic trichinosis. She had numerous hard masses beneath the skin of
her legs, which were locally irritable when they first appeared, though
they soon ceased to give trouble. At first it was thought that the
tumours were multiple fibromata, but on cutting one out and submitting
it to microscopic examination it was found to contain encapsuled
trichinæ.
D’ARCY POWER.
CHAPTER XVI
ELECTRIC GENERATING WORKS
This article is simply an attempt to apply expert knowledge to the
practical purpose of safe-guarding those employed in electrical works.
The writer was a member of the Home Office Committee on Dangerous
Trades, and of necessity much that now appears is a repetition of what
was presented by that Committee in its Second Interim Report in 1897.
It is satisfactory to record that many of the suggestions offered by
the Committee have been accepted without hesitation and acted upon.
The generation and distribution of electrical energy, so far as it
relates to the health and safety of the workers, may be considered
under the following heads:--
(_a_) The risk of shock by accidentally coming in contact with
conductors at high pressure, whether in generating or transformer
stations.
(_b_) The fencing of all mill-gearing and machinery used for the
conversion of mechanical into electrical energy.
(_c_) The health of the operatives.
Before dealing with these specific points it may be desirable to
state in general terms what is meant by “generating and transformer
stations.” A generating station is a place in which, by the aid of
steam, gas, water, or other source of power, mechanism is used for
driving dynamos, which are machines for converting mechanical into
electrical energy, whether for producing light, driving machinery,
running railways, tramcars; for depositing metals, plating, welding,
heating, etc., etc., or for charging storage batteries.
Transformer stations vary in size from buildings of considerable
proportions to mere cellars, or even boxes too small for entry. In such
places are found appliances for the conversion of small current at
high pressure to large current at low pressure, or _vice versâ_.
Stationary transformers are used for alternating currents, while rotary
converters or transformers, requiring more room and attention, are
necessary for direct currents.
To appreciate the risks hereafter described, a statement in the most
elementary terms now follows, showing how mechanism can produce the
foregoing results.
A conductor of electricity, _e.g._, a piece of copper wire made
to traverse a magnetic field (that is, the space between the poles
of a magnet), has an electro-motive force, or difference of electric
pressure, set up in its ends, which depends upon its length in the
field, its velocity, and the strength of the field, being in fact
proportionate to the product of these three. As the movement cannot
continue in a limited field in one direction indefinitely, it must be
reversed, thus causing a reversal in the electrical state of the ends.
If the ends slide on stationary conductors, these too will share the
electrical state of the ends, and alternating current will pass between
these stationary conductors if they are joined by a conducting wire.
This current will be greater as the difference of pressure is greater
and as the electrical resistance of the conducting circuit is less.
In order to increase the effect of a moving conductor, its length may
be increased by suitable windings, the arrangement of which, however,
cannot be described in these pages. The effectiveness, moreover, is
enormously increased by winding over a laminated iron core, which
greatly increases the magnetic force. If, instead of connecting the
ends to sliding contact rings from which an alternating current is
taken off by stationary contact brushes, the ends of a number of coils
are joined to a series of insulated commutator bars, it is possible by
suitable connections so to arrange that all the coils remain in action
and that the points of the commutator rubbed by the fixed conducting
brushes do not change in their electrical pressure, so that a direct
(_i.e._, non-alternating) current is the result. This is desirable
for arc lighting, and is essential for charging batteries and generally
for effecting chemical change.
Dynamos of many forms are made. Sometimes the field magnets revolve,
the armature being stationary, but usually the reverse is the case.
In some machines there are two poles only, in others, many. The main
principle, however, is the same in all.
When the direction of the current is not commutated, it will, in
consequence of the rapid revolution of the armature, alternate or
change its direction very frequently, 100 alternations in a second
being not uncommon. The currents produced may be classed as low
pressure, high pressure, and extra high pressure. Currents at low
pressure distributed from generating stations are invariably direct.
High pressure currents are distributed either as direct or alternating.
One, if not more, extra high pressure station in Great Britain supplies
alternating current.
Opinions differ as to the pressure at which these currents become
dangerous. The recommendation made by the Committee before referred
to was to the effect that currents should be considered dangerous at
700 volts direct, and 350 alternating; and that all metal conductors
carrying a current equal to or greater than this should be deemed to
be at high pressure. It is from currents at high pressure that we may
expect special danger to life from shocks caused by parts of the body
coming in contact with conductors differing considerably in pressure,
not necessarily metal conductors, for one contact may be with earth,
especially if the ground is damp. American experts have laid down that
the pressure which may be relied upon to cause death is 1500 volts.
According to this standard, the Home Office Committee would appear to
have erred on the side of extreme caution. Subsequent events, however,
have proved that this is hardly the case. Possibilities fore-shadowed
in section 19 of its report have almost literally been realised in a
large factory at Bradford, where a lad, aged nineteen, engaged in doing
repairs, came in contact with a frame of an arc lamp. He was working
in a warm cellar, his boots were damp, and, unhappily, he stood upon
an earthed metal plate. The frame of the lamp accidentally touched
formed part of the circuit. A leakage from the positive brush to the
dynamo-frame, which was earthed, created a short circuit between the
frame of the dynamo and the frame of the lamp, the man forming a part
of the circuit. A direct current, of 250 volts only, passed through
his feet, probably through his heart, causing death. It is much to
be regretted that artificial respiration, as recommended by eminent
authorities and described in the report of the Committee, was not
attempted. An article published in _Nature_ of 23rd August 1900,
gives in detail a description of experiments carried out by Professor
H. F. Weber, of the Zurich Polytechnic, to decide what pressure is
dangerous on electric railways with overhead trolley wires. These
experiments were undertaken owing to a dissension, between a firm
of electrical engineers and the Baden authorities, as to the proper
pressure to be used for two electric railways to be worked by the
3-phase alternating current. The details showing the physiological
effects on the human body are highly interesting, Professor Weber
allowing himself to be the medium of the experiments, and constituting
himself the measuring instrument. Two series of experiments were made.
In the first, a person seized the two bare leads with both hands
simultaneously, or both of the leads fell upon a bare part of the human
body. In the second, a bare part of a person standing on the railway,
or on a car, came into contact with one of the leads. Professor Weber
draws the following conclusions:--
“A simultaneous touching of both of the poles of an alternating
current circuit is dangerous as soon as the pressure exceeds 100
volts; and since it is impossible to set one’s self free, the
case must be regarded as fatal whenever immediate help is not at
hand.”
“These results,” continues the article, “are consistent with several
disasters which have happened in practical life.
“In 1896, in Horgen (Switzerland), a man, to prevent himself falling
from a ladder, seized with both his hands two non-insulated leads with
a P.D. of 240 volts between them, and was immediately killed. In a mine
in Silesia, a workman seized in the same manner some non-insulated
leads and was killed, on account of his being unable to release them,
the P.D. being 300 volts. In the Electric Central Station in Olten,
a workman, desirous of proving to his companions that a pressure of
500 volts was quite safe, seized both of the leads and was killed
instantly. From this it is obvious that the general opinion of a
pressure of 500 volts not being dangerous does not hold good, the limit
being much lower. In spite of the great number of disasters which have
already happened, the danger does not seem to have been generally
appreciated, and workmen and erectors are often seen to deal with leads
and apparatus of relatively high pressures in the most careless manner.
That disasters have not taken place oftener may be due to the fact that
in most cases help has been readily at hand.”
In the second series of experiments the person is supposed to stand on
one of the poles itself, namely, the earth, being rather well insulated
by means of his shoes. In this case the conclusion arrived at is that--
“To touch one of the poles is not dangerous as long as the
pressure does not exceed about 1000 volts; the intense
stinging which appears at the first slight touching serves as
a protection against the danger, for the hand is instinctively
drawn back rapidly.
“The main result of these experiments is, then, that all
pressures between 100 and 1000 volts must be regarded as equally
dangerous, and consequently there is no reason for not using the
higher pressures between 500 and 1000 volts, especially as they
lead to greater economy in the working of the electric railway.
Further, there is only a very little chance of the passengers
or other persons coming into contact with both of the leads. To
this danger the employés only are exposed, and being generally
people with some electric training, they are acquainted with the
danger, and may be supposed to be sufficiently careful.”
It is of interest to note that the authorities, after the
investigation, decided upon allowing a working pressure of 750 volts.
Both series of experiments relate to alternating currents.
There is perhaps no better method of impressing upon people the dangers
of electric shock than by stating briefly, as under, some of the fatal
accidents that have happened during the last few years in electrical
stations, factories, and other places in the United Kingdom. Fatalities
in transformer stations will be separately noticed. The voltages in
most cases were from 2000 to 2400; in one case 1000, and in another (a
high pressure station) 10,000:--
1. Touching exposed terminals when manipulating a switch at a
generating station.
2. Accidentally grasping an insufficiently protected volt meter wire.
3. When up a ladder in a central station, deceased accidentally came in
contact with a highly charged metal conductor.
4. When oiling the bearing of an alternating machine, and using a metal
can, the can came in contact with a highly charged conductor. Deceased
had one hand on a metal rail intended for the protection of the
machinery. The current passed through the metal can, through his body,
and thence to earth.
5. When doing repairs at the back of a switch at a central station,
deceased accidentally touched two metallic connections varying greatly
in pressure.
6. When a workman was carrying an iron ladder in a factory the ladder
touched a highly charged conductor in an arc lamp circuit, the current
passing to earth through the body of deceased.
7. Whilst performing test operations at an electrical station.
8. An operative was putting some capping on a casing in an electric
lighting works. Inadvertently he drove a screw through the insulation
of a cable then “dead.” The current was turned on. The operative
touched the screw head and at the same time an adjacent water-pipe. The
current passed from the screw through his body and the water-pipe to
earth. (A brother of this man was killed in a transformer chamber.)
9. An operative, when at work in a factory, accidentally stumbled, and
seized hold of a wire stay supporting a pole of an arc lamp. There must
have been a defect in the insulation, and this stay was highly charged,
the man being killed instantaneously.
10. When covering wires leading to a switch, deceased fell across the
terminals of one of the machines.
11. By accidentally touching a synchronising switch in a generating
station when doing repairs. The current passed through deceased’s body
to an iron column that he happened to be touching at the same time.
12. A boy employed in a large steel factory accidentally came in
contact with the frame of an arc lamp lowered for the purpose of
recarbonising.
13. An operative employed in ironworks accidentally touched a wire used
for raising and lowering an electric arc lamp. He was found on his back
in a weighing-cabin. Another workman thought that he was in a fit, and
went to his assistance. Both men received fatal shocks.
14. At an extra high pressure generating station an operative was found
dead on the floor. Medical evidence tended to show the difficulty of
stating with certainty whether the man died from shock or from heart
disease. The coroner’s jury, however, found that death was due to
asphyxia produced by electric shock.
Our attention may now be turned to fatalities in transformer stations,
or boxes in which alternating currents at high pressure are converted
to large currents at low pressure. A dangerous pressure is found in
the main conductors, this being reduced by causing induced current in
the consumer’s circuit, the strength depending upon the proportion of
the windings in the primary and the secondary circuits, the secondary
being in no way metallically connected with the high pressure main.
Under these circumstances, and under normal conditions, the safety of
the consumer should be secured. That, unhappily, cannot be said so far
as relates to the workers, whose duties take them near the transforming
apparatus. It is undesirable to give names, places, or dates, but the
following brief summary of fatal accidents that have happened during
recent years in transformer stations may be relied upon as being
generally accurate. Many non-fatal accidents have happened, but these
are not noticed.
1. Attempting to assist a servant of an electrical company, who was
working in a cellar on the consumer’s premises, and who received a
severe but not fatal shock.
2. Killed when pulling back the slack of a main wire in a street
surface-box.
3. Accidental contact with undischarged and unfenced omnibus bar in
high pressure distributing station.
4. A second accident of the same kind as the last foregoing, and at the
same station.
5. Killed when dusting a high pressure fuse in a cellar transformer.
6. Contact with dangerously placed terminals at a transformer chamber
in a cellar.
7. Accidentally touching a high pressure terminal when cleaning or
repairing in a street transformer chamber.
8. Touching a highly charged transformer frame in a street chamber.
Defective insulation in the main conductor led to leakage and to the
frame becoming highly charged.
9. When descending by an iron ladder to a street transformer chamber,
the operative came in contact with a highly charged frame of a
transformer.
10. Two workmen were removing a transformer from a corporation
sub-station. They accidentally put on a wrong switch. The exposed ends
of the cable, which were in contact with the transformer frame, caused
the frame to become highly charged. Two men touching the frame were
killed, others were seriously injured.
11. A workman, when making a connection in a corporation sub-station,
came in contact with the bared ends of a highly charged cable.
12. Killed by grasping an imperfectly insulated connection in a street
transformer pit.
Such accidents are not confined to operatives. The following are known
to have been due to electric shock. At Bournemouth, ’bus horses outside
a hotel fell down dead. At Norwich, dogs that passed a certain spot
uttered an unearthly howl. At Hartlepool an overhead wire broke,
killing a horse. Two cabmen who came to the rescue received severe
shocks. The _Matin_ of 27th January 1897 describes how two horses
were suddenly struck down by the current from a subterranean cable used
for running an electrical tram. In Dublin a gentleman was standing
close to an electric lamp in the street, which he states paralysed
him, causing him to fall “like a lump of lead.” Others going to his
assistance received shocks similar to those of the two cabmen at
Hartlepool. The _Melbourne Argus_ records a fatality to a young
man who climbed a pole supporting a heavily charged wire, which he
touched. “This,” says the _Argus_, “is not the first terrible
accident which has happened in connection with the lighting of the city
and suburbs. At the Richmond works of the New Australian Electric Light
Company, whose wires were concerned in Saturday’s fatality, a workman
or overseer was killed instantaneously through touching a “live” wire.
Another, who was engaged in the A. U. Alcock works in the city was
more fortunate. He seized a wire with one hand to prevent himself from
falling, and was so seriously shocked by the current that he could
not let go. Another workman, observing his predicament, cut the wire,
and he fell to the ground. A third and even more remarkable case than
the others occurred some time ago in Russell Street. There had been a
violent storm, and a post carrying electric lighting wires had been
blown to the ground. In the fall some of the wires broke and trailed
across the footway. A pedestrian idly picked up the end of one of the
broken wires. In a moment he was kicking and plunging upon the ground,
unable to release his hold of the wire. Another pedestrian, who saw
the accident, and who recognised that it was a struggle with death,
hastened to the rescue, and attempted with all his strength and both
his hands to drag the first man into safety. His good heart cost him
his life.”
Enough has been said to show that a shock, whether from a direct or an
alternating current at high pressure, is highly dangerous to life, many
authorities being of opinion that the alternating is the more deadly
current of the two.
Where a direct current is transformed, it is done by mechanical
appliances. The risks to operatives in such a case include those that
are incurred where machinery is left unguarded; but in dealing with
alternating currents no mechanism is used, and the risk is confined
to the danger from shock. The cases quoted show, better than detailed
explanations, the manner in which these shocks are received, and it
cannot be out of place to urge the importance of insisting on all known
precautionary measures for the protection of those whose duties take
them into transformer stations. The number of such places increases
year by year, and they are likely to increase to a greater extent in
these days, when induction motors, driven by alternating currents,
are so rapidly coming in favour for running machinery in factories.
Modern science has shown that the alternating current can be used in
this manner, and that by substituting the alternating for the direct
current, power may be economically conveyed for considerable distances,
the advantages of the alternating current being the ready conversion of
high to low pressure, and hence the saving of copper in the conducting
wires, the further saving of the cost of brushes and commutators,
whilst the absence of “sparking” lessens the risk of fire, and the
non-handling of brushes, etc., reduces the danger of shock. These
advantages were referred to and summarised in the report of Mr Bremner
Davis, reproduced in the Report of the Chief Inspector of Factories for
the year 1898.
Science has not yet explained what is the mystic force known as
“electricity.” Its effects, however, are known. How the human system is
affected by contact with a conductor charged with electricity at high
pressure has been fully considered by eminent scientific men, such as
Drs D’Arsonval, Goelet, Hedley, and Lewis Jones, to whom the public
are indebted for suggestions on which were based the excellent rules
published by the _Electrical Review_, for dealing with apparent
death from electric shock. A copy of these suggestions is appended, and
one should be found and understood in all places where electricity is
used.
The highly interesting question as to how death from electric shock
is caused, is ably dealt with by Professor Thomas Oliver, who in
an article published in the _British Medical Journal_ of 15th
January 1898, placed the public in possession of knowledge gained by
experiments and long and careful study. He believes that electricity
kills either by suddenly arresting respiration, or by stopping the
heart’s action. A series of experiments carried out by him showed
that in most instances the effect of the electric shock was felt
principally by the heart. This organ immediately ceased to beat where
very high pressure currents were used, whilst breathing might continue
a few minutes longer. Within the last few months, Drs Prevost and
Battelli, of the Geneva University, have instituted a fresh series
of experiments, and they have found that whether the direct or the
alternating current is used, death comes, practically speaking, in
the manner stated by Dr Oliver, viz., by paralysis of the heart. Dogs
were in this way immediately killed, and yet the breathing continued
for a few minutes afterwards. When fairly high voltages were employed,
_e.g._ 550 volts, these experimenters found that the heart was
suddenly arrested by one shock, and that, while the breathing was
at the same time suspended for a few seconds, respiration gradually
returned in a feeble and superficial manner, and soon finally ceased.
After all, the main question is, how to avoid death from electricity;
and the obvious reply is, avoid shock. This is no simple matter, but
to some extent a solution is found in the recommendations made by the
Home Office Committee, which were largely based upon the opinions of
Professor C. V. Boys (a member of the Committee), and other eminent
electricians. These recommendations are here reproduced in appendix
form. In the light, however, of fresh experience showing that an
artisan working in a factory was killed by direct current at 250 volts,
prudence may hereafter suggest that precautions should be taken in
places where the voltage is lower than that named by the report.
The operatives engaged in electrical works do not appear to be subject
to any exceptional risks so far as health is concerned; but those
who work where plates for storage-batteries are manufactured, or who
subsequently manipulate the plates, are liable to suffer from plumbism.
Special Rules founded upon the recommendations of the Home Office
Committee appointed in 1893, and known as the “White Lead Committee,”
were issued by the Home Office. These apply to electric accumulator
works, and require the provision of bath and lavatory accommodation,
hot and cold water, soap, brushes, towels, respirators, and overall
suits for persons employed in mixing dry red lead and dry litharge, and
gloves and aprons for persons engaged in “rubbing,” that is, rubbing
red lead into the interstices of the lead plates.
Rooms in which accumulator batteries are found are always
well-ventilated, preventing any undue accumulation of oxygen and
hydrogen gas given off during the charging process, but in electric
launches or tramcars, where the accumulator cells are shut up in
confined spaces, dangerous explosions have taken place.
So far as the fencing of machinery and mill-gearing used in the
generation of electricity is concerned, common sense points to
precautions being taken, such as are required in all factories. All
dangerous mill-gearing, such as cranks and fly-wheels of engines,
shafting, wheels, drums, pulleys, etc., for communicating the first
moving power to the machines, should be securely fenced. In doing this,
however, special care should be observed lest in removing one source
of danger another may be created. In ordinary factories fencing-rails
are almost universally of metal. These rails in generating stations
should be of wood or other insulating material; for should, perchance,
an operative make an accidental contact with metal at high pressure in
the circuit, at the same time touching any part of a metal rail, the
current would pass through his body to earth, always assuming that the
rails are not sufficiently insulated from the earth. Such accidents
have happened, and are liable to occur again, to men engaged in oiling
bearings, adjusting brushes, cleaning commutators, collector-rings,
etc., the risk of course being increased should any defect in
insulation cause the current to run to frame. Terrible fatalities
due to unfenced machinery have occurred in generating stations, as
in other works, none more painful perhaps than one that happened to
an engine-driver at an Electric Supply Company’s works, who, when
examining bearings, fell into some part of the machinery driven by a
7000 horse-power engine, and was torn to pieces.
As time goes on, there appears to be a fuller realisation of the
dangers incurred, and it is not too much to expect that those in
positions of responsibility will heartily co-operate with public
officials in taking precautions suggested by prudence and common sense.
APPENDIX I.
The following recommendations were made by the Dangerous Trades
Committee of the Home Office. For the purposes of these regulations
a station where the direct current generated is at 700 volts or any
higher number, or where the alternating current generated is at 350
volts or any higher number, shall be considered a “high pressure
station,” and all metal conductors, whether they be on the dynamos,
the switchboard, the mains, or any other part of the station carrying
a current at a pressure equal to or greater than that above mentioned,
shall be deemed to be at “high pressure.”
The Committee recommend that the following regulations should be
applied in all those cases mentioned in paragraph 1 where electricity
at high pressure is in use. It is not intended that they should be
applied to low pressure systems:--
1. The frames and bed plates of all generating machines shall be
efficiently connected to earth.
2. The rails fencing dynamos, or other generating machines,
shall be made of wood or other non-conducting material.
3. All terminals, collecting brushes, main connectors, parts of
dynamos, motors or other appliances, to which neither Regulation
No. (6) nor No. (7) applies, shall be so placed, covered, or
fenced with non-conducting materials, that no person can touch
accidentally, either with his body, clothing, or any conducting
tool, two parts differing from each other by an amount which
constitutes a high pressure. This rule is to be read in
connection with No. 4.
4. The floors of all places where it would be possible to make
connection with metal at high pressure shall be covered with
an insulating mat of suitable material and kept in a state of
efficient insulation.
5. The material use for wiping or cleaning the commutator strips
or collector rings of dynamos, motors, or rotary converters of
any form shall be applied by means of an insulating handle.
6. In switchrooms and on the front of switchboards, the main
switches, main fuses, main terminals, omnibus bars, and all
other metallic parts shall be insulated or arranged in such
manner as to render it impossible for any person by accident or
inadvertence to touch them.
7. The backs of all switchboards shall be kept closed, except
for the purpose of alterations or repairs. When such work
has to be carried on either at the back or at the front of
switchboards, the following regulations shall apply:--
(_a_) No person except a skilled electrician, or a
workman under his personal and immediate supervision,
shall be employed when any part is at high pressure.
(_b_) No extensive or serious repairs shall be
executed upon metal which is at high pressure.
(_c_) Where the alterations or repairs are not of
an extensive or serious character, all metallic parts at
high pressure shall be covered with an insulating cap or
protected by some form of insulating covering, only one
part, or several at the same pressure, to be exposed at
any one time.
8. All switchboards erected after the application of these Rules
shall have, at the back, a clear space of at least four feet.
This space shall not be utilised as a store room or lumber room,
or be obstructed in any manner.
9. Any person at work upon a cable or portion of the mains under
high pressure shall wear indiarubber gloves on both hands.
10. All aerial high pressure conductors in factories or
workshops shall either be insulated over their entire length,
and supported at such frequent intervals that, in the event
of breakage, they shall not come within reach at places where
persons are liable to pass or to be employed, or shall be so
placed and arranged as to comply with the requirements relating
to such wires in streets enjoined by the Board of Trade.
11. The gloves shall be supplied by the occupier, and it shall
be the duty of the manager to see that they are in a proper
state of repair, and are worn by the workpeople.
12. No examinations, repairs, or alterations necessitating the
handling of mains, wires, machines, or other apparatus, shall be
carried on except in cases of urgent necessity while such parts
are under high pressure, and all such work shall be done under
the personal supervision of an electrical engineer or competent
manager or foreman.
13. Where operations are being conducted upon mains from which
the current has been cut off, the switch shall be locked and
precautions taken that it shall not be unlocked except by the
person in charge of the station on his being satisfied that the
danger is at an end.
14. Every vessel used for lubricating purposes shall be so
constructed that it cannot act as a conductor between the hand
and anything touched.
15. Metal transformer boxes shall be efficiently connected to
earth, and so constructed that in the event of “running to
frame” the earth connection will not be broken by the removal of
the fuse box or any other part of the box.
16. Transformer cases, iron ladders, and all permanent metallic
parts contained within the transformer chamber, and not forming
part of the electric circuit, shall be metallically connected
together.
17. All holes in transformer cases, through which high pressure
conductors pass, shall be lined or bushed with suitable and
effective non-conducting material.
18. All high pressure connections within a transformer chamber
shall be so protected with insulating material that it shall be
impossible to touch them.
19. Switches which can be conveniently operated from the outside
for cutting off both the high and low pressure connections of
the transformers shall be fitted in all transformer chambers
erected after the application of these Rules, and in all
existing chambers, unless it is proved to the satisfaction
of Her Majesty’s Chief Inspector of Factories that such an
arrangement would be attended by special difficulty.
20. Each post or support where series arc lighting is employed
shall be provided with means for completely disconnecting the
arc lamps from the mains, without disturbing the action of the
other lamps.
21. All persons engaged in electrical works shall be made fully
aware of the dangerous parts of the machinery, cables, and their
connections, and shall be practically instructed in methods of
artificial respiration--that known as Sylvester’s is both simple
and efficacious. Rules for artificial respiration, and for the
restoration of persons apparently killed or injured, shall at
all times be kept affixed in the station. All persons engaged
in the works shall thoroughly understand these rules and be
capable of putting them into practice. In the event of a person
being rendered unconscious by an electric shock, artificial
respiration shall, on the careful removal of the body from its
electrical contact, be at once resorted to, and a qualified
medical man immediately summoned.
22. All accidents occurring in generating stations or
transformer chambers shall be notified according to the
provision of section 18 of the Factory and Workshop Act, 1895.
* * * * *
The Committee feel that any set of special rules framed for
the safety of the workpeople in this industry must imperfectly
realise their object if a specially qualified person be not
retained to advise the Secretary of State or Her Majesty’s Chief
Inspector of Factories on matters requiring technical knowledge
of electricity.
H. J. TENNANT.
MAY TENNANT.
THOMAS OLIVER, M.D.
C. V. BOYS.
H. P. SMITH.
APPENDIX II.
_The “Electrical Review’s” Suggestions for dealing with Apparent
Death from Electric Shock._
The following suggestions are based on the recommendations of Drs
D’Arsonval, Goelet, Hedley, and Lewis Jones, for the treatment of
persons apparently killed by electricity:--
_Apparent Death._--In many cases where persons receive
electric shocks, death is only apparent, and animation may be
restored if efforts at resuscitation are not too long delayed.
_Method of Resuscitation._--The method of resuscitation
resorted to should be that known as artificial respiration.
Efforts to induce respiration should not be relaxed until
breathing is fully and normally restored, or until it is
absolutely certain that life is extinct.
_Danger of Seizing the Victim’s Body._--If the accident has
been due to contact with a “live” or faulty cable, the injured
person may retain a grasp of it. When the injured person retains
his hold of the cable it is dangerous to seize any part of him,
even the parts of the body covered by clothes.[49]
Perspiration may make the clothes damp and render them good
conductors, especially under the armpits, which would be the
part most likely to be seized.
In such a case the person who goes to the assistance of the
victim should protect his hands, whenever possible, with
indiarubber gloves.
Where gloves are not available, a thick layer of dry rags might
be used to cover the hands, or a coat or any other garment, if
made into a thick pad, might be used when pulling the victim
away from the cable or machinery.
_Send for a Medical Man at once._--No time should be lost
in sending for a qualified medical man, but in the meantime the
following efforts should be made to restore animation.
_How to Place the Body._--The body should be at once placed
upon the back and the clothes loosened. A roll made of a coat
or anything else convenient should then be placed under the
shoulders. It should be sufficiently large to prop up the spine
so that the head drops backward (see Fig. 30).
[Illustration: FIG. 30.]
[Illustration: FIG. 31.]
_Position of the Operator._--The operator should kneel
behind the subject’s head, in the manner shown in the
illustrations. He should then grasp the elbows and draw them
well over the head, so as to bring them almost together above
it, and hold them there for two or three seconds. Then he should
carry them down to the sides and front of the chest, firmly
compressing the chest by throwing his weight upon the arms.
After two or three seconds the arms should be again carried
above the head, and the operation repeated at the rate of about
16 times per minute.
_Additional Means of Resuscitation._--In addition to the
foregoing, if there be an assistant at hand, the tongue should
be seized by a cloth or handkerchief and drawn forcibly out
during the act of inspiration, _i.e._, when the arms are
extended above the head; when the arms are brought down, the
tongue should be allowed to recede. This operation should be
repeated with the same regularity as the movement of the arms.
_Stimulants to be Avoided._--According to Dr Hedley the
efforts of the bystanders to pour stimulants down the throat of
the victim should be resisted until a medical man arrives.
_Necessity of Deliberation._--It should be borne in mind
that to be successful the foregoing operations should be carried
out deliberately and methodically. There should be no haste, but
the operations should be executed vigorously.
In many respects the treatment suggested above is similar to the
method of treating apparent death by drowning.
HAMILTON P. SMITH.
CHAPTER XVII
DUST AS A CAUSE OF OCCUPATION DISEASE
_General View of the Subject._
Were it not for dust, fume, or gas, there would be little or no disease
due to occupation except such as might be caused by infection, the
breathing of air poisoned by the emanations of fellow-workmen and
exposure to cold after working in overheated rooms. Dust plays such
a prominent part in the causation of occupation disease that I have
thought it advisable to discuss the subject in a general way _apart
from_ the various industries detailed by separate writers. The
harmful effects of dusty trades have long been known. As far back as
the end of the seventeenth century, Ramazini, who was the Professor
of Medicine in Modena, and subsequently at Padua, had drawn attention
to this subject. He showed in his treatise, the _Diseases of
Artificers_, how ill-health was caused by the inhalation of subtle
particles that were offensive to human nature, and its aggravation by
the unnatural postures of the body assumed in certain occupations. He
also pleaded for the introduction of such contrivances as would lead to
the safety of the workmen and the necessity for their being medically
inspected. In these senses, therefore, he was the pioneer of the State
Medicine of our time.
Apart from anything inherently poisonous in the dust that is given
off in a particular trade, dust itself, mechanically speaking, is
prejudicial to health. A considerable length of our respiratory
passages is lined with a layer of ciliated epithelial cells,
_i.e._, cells from the free end of which project numerous
hair-like processes that execute a rhythmic bending movement, like
a field of wheat when a current of wind passes over it, and whose
function it is, owing to the cilia actively bending in an outward
direction, to prevent dust getting into the lungs, and to favour its
expulsion should it have gained access to the smaller bronchial tubes.
Nature, anticipating that dust would be drawn into the lungs in
inspiration, has therefore provided this means for making its access as
difficult as possible, and of effecting its removal when the breathing
of the dust is intermittent. When animals are exposed for a period to a
sooty atmosphere and are subsequently killed, their lungs are found to
be perfectly black, but if other animals, after similar exposure, are
allowed freedom in the open air, the lungs after death exhibit few dark
patches. One of the effects of recurrent inflammation of the bronchial
tubes is to bring about detachment and removal of this ciliated
epithelium, and with its disappearance an important safeguard to the
lungs is lost.
Dust affects the body by being deposited upon the skin, hair, eyelids,
and the oro-nasal passages. Through the mouth and nose it is aspirated
into the lungs during respiration, or it reaches the alimentary canal
through the saliva or with the food.
When the skin becomes affected through an individual working at a dusty
trade, the lesions thus caused are called _dermatoconioses_,
similar affections of the lungs constitute _pneumoconioses_,
while those of the gastro-intestinal tract are known as
_enteroconioses_. Although the intestine, as in plumbism, is
one of the most important and frequent channels by which industrial
poisoning occurs, yet, pathologically speaking, the lesions of this
canal are the least definite.
So far as _dermatoconioses_ or inflammatory affections of the skin
are concerned, it is mostly in industries in which dry dust is given
off that these are met with, as, for example, in dry bronzing, but
certain fumes also cause them, as is seen in the smelting of antimony.
No portion of the skin is free from the possible contamination by
dust, but it is upon the hair, beard, eyelids, under the nails, upon
the lips, and inside the nostrils, upon any uncovered part of the body
when the individual is at work, or where the clothing loosely meets
the skin, also in such flexures of the body as the armpits and the
groins, and where the garters fix the stockings, that the effects of
dust are mostly observed upon the skin. When the factory is warm, or
the work heavy, and the individual perspires freely, the dust mingling
with the products given off by the humid skin either falls off in
muddy drops of sweat, or it cakes and forms crusts. As a consequence,
there is a variety of lesions, _e.g._, simple irritation or
itchiness, known as pruritus; inflammation or erythema proceeding to
eczema; or, as in the case of antimony smelters, vesicles that become
pustular, and in arsenic grinders, ulceration. Since dust that
of itself is harmless can induce disorders by mechanically blocking
the pores of the skin and the excretory ducts of glands, so, too, can
harmful dusts act, but they produce in addition certain irritating
and poisonous effects proper to the peculiar character of the dust.
Some dusts are crystalline or sharp-pointed, and penetrate readily and
deeply, while others have a distinct caustic action, and erode or eat
away the tissues, as is the case with the bichromate compounds. Some
forms of dust again are composed of soft particles that of themselves
inflict little local damage, and only become harmful like flour in
forming plugs; while attached to some forms of animal products, such
as horsehair used in brushmaking, are micro-organisms that become
a source of danger. It is unnecessary to mention the various skin
affections or _dermatoconioses_ produced by dust. They are all
more or less the result of inflammation. In many of the erythematous
forms of skin eruption the redness of the skin may simply be the result
of the mechanical action of the dust, or the dust may be absorbed.
One consequence of local irritation may be the formation of vesicles.
Sometimes the itchiness becomes so great that scratching is resorted
to and there follows eczema. Where the vesicles become pustular,
this is generally due to the action of metallic poisons of an acrid
character, or to poisons of an animal nature, as in anthrax. Ulceration
of the skin, on the other hand, is the result of such caustic action
as that induced by arsenic and the chrome compounds. The accompanying
Photographs show various forms of dermatitis that occur in flax
spinners, also of diseases of the finger nails in hide dressers. They
are introduced here not as illustrating the harmful effects of dust,
for they occur in the wet processes of an industry, but as indicating
what is meant by the term _dermatoconioses_.
[Illustration: FIG. 32.--Mild form of Dermatitis
in Flax spinner (moist method); girl aged 16. Three years’
service in Factory. (Dr Glibert).
FIG. 33.--Medium degree of Dermatitis in Flax
spinner (moist method); woman aged 33. Eighteen years’
service in Factory. (Dr Glibert).
SKIN DISEASES OF FLAX SPINNERS.
[Illustration:
FIG. 34.--Severe form of Dermatitis in Flax spinner
(moist method); woman aged 19. Eight years’ service in Factory.
The small punched-out looking sore on thumb resembles what is
known to medical men as “Specific” ulceration, but it is in no
ways connected with it. (Dr Glibert).
FIG. 35.--Severe form of Dermatitis in Flax spinner
(moist method); woman aged 19. Eight years’ service in Factory.
Observe special round callosity on ulnar side of hand, an
affection first pointed out by Dr Van Eecloo of Lille. (Dr
Glibert).
SKIN DISEASES OF FLAX SPINNERS.]
_Skin Diseases of Flax Workers._
It is through the kindness of Dr Glibert, Medical Inspector, Labour
Office, Belgium, that I am able to show in the accompanying Photographs
these particular lesions of the skin. The four Photographs in which the
palmar surface of the hand is shown, are taken from flax workers. They
indicate varying degrees of erosion, due to the frequent contact of
the hands of the female worker with the irritating materials contained
in the liquid used for spinning. At the commencement of the malady,
as is well shown in the Photographs, the lesion is limited to an
exfoliation of the epidermis, and this is not accompanied either by
pain, pruritus, or functional trouble of any kind. Later on the dermis
itself, or true skin, becomes involved at certain places, usually very
few, and at these spots there exists considerable irritation, also a
sensation of painful pricking, especially pronounced after working,
and when the wounds are brought into contact with the air. As a rule,
the malady does not proceed beyond this stage, but in some rather rare
cases, met with mostly during severe weather, the ulceration tends to
pass into the deeper tissues of the skin, and to assume an appearance
which, to an unskilled observer, recalls the lesions met with in
syphilis. There is nothing, however, in the flax workers’ dermatitis
to confirm this suspicion. It is necessary to remark that there is
never produced erythema, the formation of vesicles or a vesico-pustular
eruption, and still less the glossy and bright appearance of the skin
of the hand observed in eczema of a lichenoid character. Dr Glibert
has frequently met with this form of eczema, to which Dr Leloir and
his pupil Lefèbvre have drawn attention, but the ulcerative type of
dermatitis indicated in the accompanying Photographs is absolutely
distinct from these, and must not be confounded with them. It is only
right to mention that although dermatitis has been observed in Belgian
flax spinners, Belfast operatives similarly employed do not, according
to Dr Purdon, suffer.
_Diseases of Nails in Furriers._
The two Photographs showing the back of the hands of workmen who scrape
rabbit and hares’ skins used in the manufacture of artificial furs
exhibit an affection of the nails, to which Dr Glibert of the Belgian
Labour Office drew attention in the Annual Report of the Inspection
of Labour, 1896. The work of separating the layer of aponeurosis,
which occurs on the under surface of the hide, causes in the dresser a
special disease of the nails of the fingers. The groove under the nail
becomes deeper, the nail is subsequently detached from the finger and
falls off, either by some peculiar pathological process unaccompanied
by ulceration, or by one of an inflammatory nature akin to what occurs
in whitlow. The malady may attack all the fingers of the two hands,
but it seizes by preference the thumb, the middle and ring fingers of
the right hand. It is a common affection in fur-pullers in Belgium. Dr
Glibert is the only writer I know who has described it. Of 22 workmen
whom he examined, it was present in 18. He regards the lesion as
distinctly microbic.
[Illustration: FIG. 36.--Disease of Finger Nails
in Hide dressers. Man, aged 35. Fifteen years’ service. (Dr
Glibert).
FIG. 37.--Severe type of disease of Finger Nails
in a Hide dresser. Man, aged 49. Twenty years’ service. (Dr
Glibert).
DISEASE OF FINGER NAILS IN FURRIERS.]
_Lung Diseases due to Dust._
In pneumoconiosis the lung is altered in structure as the result of
irritation caused by inhaled dust. A healthy lung is composed of loose
spongy tissue, through which run in all directions the bronchial tubes
and their fine ramifications (see Fig. 38). The essential part of the
lung is made up of alveoli or air-cells, like the meshes of a net.
Just as an ordinary net is made of strands of cord, so are the walls
of the pulmonary alveoli formed of delicate lines of connective and
elastic tissue, in which run capillary blood-vessels. The partitions
thus formed are coated on both sides by a layer of flattened epithelial
cells. It is this loose and almost uncovered condition of the pulmonary
capillaries that allows of the rapid interchange of gases between
the blood circulating in the alveolar walls and the air in the lung
during respiration. Nature has placed certain obstacles in the way of
particles of dust gaining easy access to the lungs, to wit, the narrow
openings of the nostrils, the mucus secreted by the lining membrane of
the nose, and of the trachea and bronchi; the narrow chink between the
larynx and trachea known as the vocal chords, the ciliated epithelium
already described, and a mechanical difficulty generally; so that while
even with forced inspiration it is not easy for dust to be carried into
the lungs, yet the fact remains that where an individual is working
in the dusty atmosphere of a factory for several hours a day, week
after week, particles of dust ultimately find their way into the finer
bronchi, and subsequently into the pulmonary tissue itself. It is the
repeated working in a dusty atmosphere that causes the trouble. A
good deal depends, too, upon the character of the dust. Certain fine
dusts, such, for example, as flour, may for a time be arrested in the
mucus secreted by the respiratory passages, and be expectorated; while
others, such as white lead, become dissolved in the alkaline mucus, are
absorbed into the system, and thus induce constitutional poisoning.
Fine fluffy material, like that given off from cotton and flax, can
reach the lung, while sharp-pointed particles of metallic dust wound
the epithelial lining of the smaller bronchi and penetrate into their
walls, or they destroy the protecting layer of epithelium, and reach
the alveoli either directly or indirectly through the lymphatics. These
particles set up irritation in the lung, followed by a very marked
increase of its fibro-connective tissue, which encroaches upon the
spongy structure of the lung and destroys its aerating function. In
the coal-miner’s lung, for example, there can be observed small masses
of cells deeply laden with carbon particles surrounded by a hardened
zone of altered lung, numerous black streaks underneath the pleura or
covering of the lungs, ink-like dots in the walls of the small bronchi,
and enlargement with pigmentation of the bronchial glands. The special
pathological changes in the lungs in the various pneumoconioses are
peribronchitis, and a great increase of the fibro-connective tissue,
whereby the lung becomes converted into a hard and almost solid organ,
incapable of carrying on the work of respiration. Hence are explained
the difficulty and shortness of breath in people thus affected with
what is called fibrosis of the lung. On examining microscopically a
portion of lung that has undergone this change, there can be seen
imbedded in the thickened fibrous tissue, particles of grit which
exactly correspond in shape and size with those found on examining
the dust removed from the mine in which the person works, or from the
factory, in the case of steel-grinders’ lung. The identity of the
particles of grit in the lung and those in the dust of the factory
can be additionally confirmed by chemical examination. Such, in a few
words, is the effect upon the lung caused by inhalation of the dust
generated in a dusty occupation. The newly formed fibro-connective
tissue is of low vitality, and is badly supplied with blood-vessels,
and yet it goes on increasing and encroaching more and more upon the
lung tissue, which it replaces. Although it seldom tends to break down,
the consolidated tissue notwithstanding shrinks, the chest becomes
smaller, cough more harassing, and emaciation progressive. The affected
workman is regarded as the victim of consumption, but the disease
is not necessarily _tuberculous_. Under these circumstances,
where a lung has become altered in structure and its vital resistance
diminished, it becomes an easy matter for true tuberculosis, as the
result of its specific bacillus, to be grafted on to a pneumoconiosis,
or dust lung disease. In people who have worked in a thick atmosphere
there is therefore found a form of consumption due to the inhalation
of dust, and another the result of the tubercle bacillus, but in
old-standing cases the two are generally found combined. The tendency
of modern pathology is to look upon all pulmonary phthisis or
consumption as tuberculous, but the fact remains that phthisis can be
caused by dust. Pneumoconiosis differs from the tuberculous type of
lung disease in being more amenable to treatment in the early stage,
also in the fact that while both lungs are affected, it is the bases
rather than the apices that suffer. If the workman, for example,
leaves his dusty employment, especially in the early stages of his
illness, the malady may be arrested. Usually the march of the disease
in this form is slower than the tubercular. It is an old idea, yet
one that many seek to palm off as modern, that pulmonary consumption
is an infective disease. In factories where many persons are at work,
there are almost sure to be some who are tuberculous, and who cough and
expectorate upon the floor. The expectoration dries, is trodden under
foot, and, mingling with the dust, it rises into the atmosphere and is
inhaled. Infection from consumptive fellow-workers must therefore play
a part in the propagation of industrial phthisis, but the bulk of such
cases do not assume the character of the occupation form of fibrotic
phthisis to which we have just alluded, and which is known to occur
frequently in men employed in dusty trades conducted in the open air,
_e.g._, in masons and French millstone builders, in whom infection
is less likely to prevail, and where the breathing of close and impure
air can play no part.
[Illustration: FIG. 38.--Human Lung in health.]
[Illustration: FIG. 39.--Lead Miner’s Lung. × 70
diameters. (T. O.)]
[Illustration: FIG. 40.--Steel Grinder’s Lung. × 70
diameters. (T. O.)]
[Illustration: FIG. 41.--Coal Miner’s Lung. × 70
diameters. (T. O.)]
There are four recognised types of pneumoconioses or industrial lung
disease: (1) _Chalicosis_ or _silicosis_, due to stone dust and
siliceous material, as in masons’ phthisis; (2) _siderosis_, due to
metallic dust; (3) _anthracosis_ or coal-miners’ phthisis; and (4)
_byssinosis_, caused by inhalation of cotton particles.
_Gastro-intestinal Lesions._
The _enteroconioses_ or gastro-intestinal lesions induced by dust
are less well-defined pathological entities than the affections of
the skin and lungs, and yet they play an important part in poisoning
by such metallic dusts as lead, arsenic, and mercury. Apart from such
symptoms as vomiting, diarrhœa, and colic; which these cause, there
are the well-marked physical signs of poisoning present in the gums,
as, for example, the “blue line” in plumbism, and the loose teeth and
ulcerated gums in mercurial poisoning.
* * * * *
The attention of the reader is directed to the accompanying series of
Microphotographs as illustrations of some of the forms of dust seen
through the microscope, to which workpeople in various trades are
exposed. Apart from the poisonous character of any particular kind of
dust, _e.g._, that of lead and arsenic, the presence of chemical
irritants inherent in the dust itself as in bichromate compounds, and
the clinging of micro-organisms to such animal products as horsehair
and wool, there is an opinion entertained by pathologists that the
actual form of the particle of dust and its hardness are responsible
for much of the damage inflicted upon the lungs of workmen engaged in
dusty trades. Mineral and metallic particles of dust are hard and often
sharp-pointed. Theoretically, therefore, it is expected of them that
when they reach the lining membrane of the respiratory passages they
will inflict greater damage than particles of dust that are softer and
rounder. How far pathological experience supports this expectation I am
not prepared to say. The dust that is given off in various occupations
may be mineral, metallic, vegetable, or animal. I have reproduced some
Microphotographs taken from Dr Migerka’s monograph, _Staubarten in
Wort und Bild_, Vienna, 1895, and have added a few taken by Dr R.
A. Bolam and myself, of dust from various industries, supplied by H.M.
Inspectors of Factories. Some of these Microphotographs may be briefly
described:--
Fig. 42, _cement_ dust. Under the microscope are seen a few
sharp-edged little plates and amorphous masses like small clumps. The
particles are not of themselves so dangerous as might at first sight
appear. Although cement workers suffer from pulmonary disease, they
do not do so to the great extent that might be expected. Probably
the harmful effects are largely due to the hygroscopic character of
the particles and their alkaline reaction. Hirt gives the following
percentage statistics of diseases for comparison:--
-----------------+-----------+-----------+------------+-----------+
| Phthisis. | Bronchial | Emphysema. | Pneumonia.|
| | Catarrh. | | |
-----------------+-----------+-----------+------------+-----------+
Porcelain Makers | 16 | 15 | 4 | 5 |
Masons | 12.9 | 10.4 | 6.5 | 4.4 |
Cement Makers | 8 to 10 | 15 to 17 | ... | 4 |
-----------------+-----------+-----------+------------+-----------+