The hairy scalp is so stretched by the vertical tumor, that the hairs
are driven asunder; so that the tumor is in some places bald, and the
whole is rugged and uneven. At its basis, all round, till we come to
the extended part that goes away to the right shoulder, a bony edge
may be distinctly felt, as if the skull was depressed at the top: and
yet I cannot but believe, that there is no depression of the arch of
the inner table, because the man was from his childhood ever very
healthy; being never troubled with those symptoms, which usually attend
a depression of the _cranium_. From this seeming edge the _os frontis_
shoots out a great way over the _ossa nasi_, perhaps to two or three
inches beyond the frontal sinus’s; and is the basis, from which the
great pendulous tumor hangs downwards and forwards.
From the root of the nose, under the upper of the three smaller tumors,
arises a large trunk of a vein, which ramifies up to the vertical
tumor, and to the right over the upper part of the great pendulous one:
these are very conspicuous, and serve to bring back the residual blood
from the tumors: nor is it unlikely that the arteries bear a proportion
with these veins in their size, in order to supply the tumors with the
matter, which has given them their great increase; but these, lying
concealed, cannot be spoken to with any certainty.
If we compare this growth of the frontal bone with that of other
_exostoses_, I believe there may this difference be rationally
observed; that other _exostoses_ are generally attended with ulcerous
tumors, which are for the most part cancerous; and these may commence
at any age. I have now drawings, taken from the right hand of a man
of 50, which represent risings of the _radius_ and _ulna_, with the
fingers, to a most frightful degree; and these begun but six years
before, and are attended with foul running ulcers; and now the bones
of the arm and hand, on the left side, are beginning to have the same
appearances: whereas the frontal bone of the present subject appears
sound, as far as we are able to judge by examination: nor does there
appear the least disposition to ulceration in any part of it. When
this is the case, the growth generally begins while the subjects are
young; upon which we shall be more particular a little further on.
His sensation upon every part of these tumors, is exactly like that
of every other part of his skin, having not the least uneasiness upon
being handled. This poor man worked at day-labour in the fields till
some months before he came to town.
Perhaps it may not be improper to lay down the dimensions of these
tumors, as the case is so extraordinary; for the size of them is
almost incredible: but I made my drawing in the presence of several of
the gentlemen of that hospital, who allowed it to be very exact, and
precise in the expression of the parts, as well as in the dimensions.
The vertical tumor is about seven inches diameter at the basis, where
the bony edge is felt, mentioned before, and about four inches high
from that edge. From that edge, or the basis of the vertical tumor,
to the bottom of the great tumor, is ten inches; so that the length of
both, from the vertex to the end of the great one, is about 14 inches:
and upon viewing it, when he turns his side towards you, the whole
mass is eight or nine inches over all the way; hard at top, and flabby
downwards, hanging in kinds of plaits. From the eye to the opposite
outline of the great tumor is six inches; and lower down, from the
left corner of his mouth to the opposite outline of the same tumor,
eight inches. The upper small tumor, over the nose, is one inch three
quarters long by one inch and a half; the middle tumor is two inches
long from the _ala nasi_, to which it hangs, and of the same breadth;
and the lowest tumor, shaped like a goose’s egg, is four inches and a
half long by near three inches over.
This man is under the care of Mr. Crane, an eminent surgeon of St.
Bartholomew’s Hospital, who has just now taken off the lowest of
these three anterior tumors, and also the tumor mentioned, which hung
underneath to the under lid of his right eye. He intends proceeding to
take off that at the _ala nasi_ next, and so on till he takes away all
the smaller tumors first: afterwards the larger will be considered. The
substance of those cut off was intirely fat; nor was there the least
speck of blood in the lowest of the three smaller tumors; but there was
an hæmorrhage from a vessel divided in taking off that hanging to the
right eye-lid; which soon yielded to the methods he made use of, and
went on successfully till quite healed.
It is pity no one of the people of condition in the country, where
this poor man lived, took notice of him while he was a lad; because,
when the vertical tumor begun, or even after it had made some progress,
if he had been sent up to any of our hospitals, there would have been
no difficulty in curing him. This leads me to some precautions, which,
I hope, will render my account of the case of some use, considered in
a physiological light; which was my intention in thus laying it before
this learned Society.
There is a great deal of difference between injuries received in young
subjects and in adults. In the latter, the consequences are not apt
to be of so dangerous a nature as in the former (except indeed where
there happen violent fractures or wounds, which immediately dispatch
the person, young or old); because, in such as are so far advanced
in years, as that the parts have done growing, or, in other words,
are incapable of carrying the person to any larger size, preserving
the natural proportion, a tumor arising from a blow on the head would
be merely local, without extending to any neighbouring parts in so
extraordinary a manner: but in children, as in the case before you,
a tumor may increase every moment from a blow, and spread itself to
the neighbouring parts, to the ruin of the child, unless timely care
be taken to prevent it; because in such young subjects the parts are
continually growing, the vessels enlarging in their diameters, and
carrying more and more nutrition to every point, in proportion to the
nature of each individual organ, always preserving such an equilibrium,
in the distribution of the nutritive juices, as is proper to secure
the due proportion of every part as it increases: but when a tumor
arises from a blow in such a growing subject, if no wound is made, nor
suppuration brought on in the tumor, then the parts of the tumor being
only weakened, the equilibrium is destroyed, a greater flux of juices
than ordinary is carried to it, the due resistance being impaired, and
a luxuriancy of growth is produced in the place of the injury, which
greatly exceeds that of the rest of the body; and will most certainly
continue in the same manner, during the growth of the subject,
when once thus begun. In the present subject, this luxuriancy was
communicated even to the veins, which are apparent and large, and which
were before, in their natural state, scarce visible; and not only to
these, but to the very bones of the forehead: and as to the integuments
and membranes of the body, their great distensibility is well known
to every one. I have seen an _ovarium_ so distended by water, and
thickened as it grew, that it had substance enough to bear being
dressed by a tanner, and contained nine gallons, which I saw poured
into it after it was dressed. And does not every corpulent person shew
the same power of distension in the membranes and integuments of the
body, as well as wens of all kinds upon the surface?
I thought so extraordinary a case well worth the notice of the learned
members of this Society in itself; and the more so, as these few hints
fall naturally from it, to render its publication useful. We are taught
by this, how necessary it is for all such as have the management of
youth under their care, to have an early regard to every accident that
may befall children; for many times injuries of this kind have been
thought very trivial, which, being overlooked and neglected too long,
have been followed by very direful circumstances. I have known about a
young gentleman to have great hard swellings about his head, and become
epileptic, losing his senses as he advanced in years, from a blow with
the back of a book given him by a master. I am, with due respect,
The +SOCIETY+'s
Most obedient Servant,
James Parsons.
Sept. 18. 1757.
XLIII. _An Extract of the Register of the Parish of_ Great Shefford,
_near_ Lamborne, _in_ Berkshire, _for Ten Years: With Observations on
the same: In a Letter to_ Tho. Birch, _D. D. Secret. R. S. from the
Rev. Mr._ Richard Forster, _Rector of_ Great Shefford.
[Read Nov. 17, 1757.]
Great Shefford, near Lamborne, Berks, July 8. 1757.
Rev. Sir,
WHEN I settled in the country, abundant leisure enabled me to keep an
exact parish-register. I have now finished ten years, I trust, with
sufficient care, having examined every thing accurately myself. The
sight of three letters, lately published in the Transactions, upon
the subject of political arithmetic, put me upon overlooking and
methodizing my own account; which I here send you, to make what use you
think proper of it.
From Lady-day 1747. to Dº. 1757.
{ Males 73 }
Baptized { Females 75 } 148
{ Males 44 }
Buried { Females 39 } 83
---
Increase 65
{ Under 2 years of age 25
{ Between 2 & 5 4
{ 5 - 10 3
{ 10 - 20 4
{ 20 - 30 5
Buried { 30 - 40 9
{ 40 - 50 4
{ 50 - 60 4
{ 60 - 70 9
{ 70 - 80 11
{ 80 - 87 5
--
83
--
And but one alive above 87, who is 91.
The Number of People 425.
The Number of Houses 90.
The Number of Acres 2245. whereof ⅙ is waste.
I do not offer such trifling numbers as these, as a fit subject to
build a canon of life upon; but only as they may furnish us with a few
particulars, which may throw some small light upon a subject hitherto
very little cultivated: and as what has been advanced this way has been
always taken from great cities, a little from the country perhaps may
not be disagreeable.
The first observable in my numbers is, that the two infancies of human
life are exactly equal; i. e. as many die above 60 as under 2 years of
age; and that these two periods of life are by much the most sickly,
five eighths of the whole, nearly, dying in these two stages, which
renders the intermediate numbers very small.
This will give us some reason to suspect, that capital cities are very
improper to estimate the probabilities of life from. The continual flux
of people from the circumjacent country, to seek for employment, makes
the decrements of life seem much larger than they really are. London
is very remarkable upon this account; and Breslaw must receive pretty
large accessions, as a very considerable manufacture is carried on
there.
The second thing I would observe from my table is, that it confirms
what Dr. Brackenridge observes of the Isle of Wight; _viz._ that the
births are to the burials as 2 to 1 almost; ours being as 15 to 8
nearly. Now if this is the case of all the country places in England,
it will give us a strong presumption, that the increase of mankind is
much quicker than Dr. Derham’s proportion of 1 to 12; especially if we
consider,
Thirdly, That of the living not 1 in 50 dies yearly; and this in a
village not very healthy. We are situated upon the celebrated Lamborne
stream, which dries up generally in August, and leaves a stagnated
water, and stinking mud, at a critical season of the year, which bring
on a putrid fever, and make our place sometimes very sickly. In the
year 1751 we buried 17, and in 1756. 11: and therefore we may presume,
that in the healthiest parts of the nation, the proportion is still
greater, perhaps not one in 60. In order to clear up this, it were to
be wished, that the actual number of the people was known, where-ever
the bills of mortality are exhibited. All reasoning without this
preliminary is really not much better than groping in the dark.
A fourth thing observable from my numbers is, that the quantity of
people allotted to a house is too big in all former calculations: for
if we divide 425, the number of people, by 90, the number of houses,
it gives but 4.72, which is not quite 4¾ to a house; and therefore 5
to a house, I believe, is as much as ought to be allowed, taking the
nation all together. Now if the number of houses, taken in Queen Anne’s
time, be any thing near the right, with one fourth more allowed for
cottages, according to Dr. Brackenridge’s computation, we shall make
the people in England, allowing 5 to a house, to be only 4,556,550.
which appears, at first sight, to be too small a number. However, of
Shefford I would beg leave to observe, (and it is far from being the
poorest of villages) that more than two thirds of all the houses are
downright cottages, and must be excluded, one as much as another, from
any proposed assessment. Upon this foundation we must grant, that at
least half the houses in England, take towns and all together, must be
cottages, and plead an exemption from taxation all alike. And thus
the number of houses will be 1,458,096. which, multiplied by 5, will
give us the number of people, 7,290,480. If to this we add the proposed
increase, 789,558. we shall have 8,080,038 for the number of people now
alive in England.
The fifth and last thing I would observe from my numbers is, that we
may hence guess at the number of people in the whole kingdom: for
if 1871, the good acres in Shefford, demand 425 persons for their
cultivation, then will 25,300,000 good acres in England require
5,704,168 for the cultivation of the land only. Now supposing one third
part of the people only to live in towns, above what is necessary for
the cultivation of the land belonging to such towns, then we must add
2,852,084 to the above sum, which gives us 8,556,252 for the number
of people in England. It may probably here be said, that this is but
little better than reckoning at random. Indeed I allow it is so. But
then I must beg leave to observe, that it has full as good a foundation
to stand upon, as any calculation, that I have seen hitherto advanced.
It has one _datum_, viz. a certain number of persons to a certain
number of acres. It ought to be noted at the same time, that we are an
inland place, have no sort of manufacture carried on, and consequently
no accession of strangers.
If we examine the calculation arising from the consumption of wheat,
we shall see some reason to suspect, that the number of inhabitants
in England is not short of eight millions. I am persuaded I do not
exaggerate, when I affirm, that three fourths of the people north of
Trent, and in Wales, do not eat wheat: and as this is near a third
part of England, it will follow, that one fourth of the whole is left
out of the calculation, and that we must add near two millions to it to
make it complete.
Again, I compute, that in my parish there are killed annually 160
fat hogs, _viz._ above one to three persons; and that this humour of
pig-killing prevails over half of England at least, and is in some
measure indulged in all parts. Now we will suppose, that there are but
six millions of people in the nation, and that what is killed in the
northern half makes up for what is deficient by reason of towns in the
southern half; we must from hence conclude, that a million of fat hogs
are killed in England every year. Now one hog with another takes two
quarters of corn, sometimes barley, sometimes pease: if we put half
barley, we shall be under the truth. And here we shall have a million
quarters of barley, not only to balance the exportation of wheat, but
also to be equivalent to, as much bread-corn as will maintain a full
million of people.
Farther, it is well known, that the greatest part of the corn-trade
is, of late years, got into the hands of millers: and it has been
whispered about for a considerable time, and, I think, now the millers
do not deny it, that _some_ whiting is carried to all the great mills.
The excuse alleged for it is, that it makes the flour _wet_, and
consequently _bake_, the better. I am rather inclined to be of opinion,
that it is to give a colour to something that wants colour. And indeed,
who-ever tastes the common bakers bread against a piece of genuine
wheat-bread, will have some reason to suspect, that all is not gold,
that glitters. Every body knows, that the millers buy large quantities
of barley and pease, they say, to fat hogs: but then they have pollard,
middlings, _&c._ to fat them with; and so may possibly mix the barley
and pease with wheat to grind. But as this is all surmise, I would have
no more weight laid upon it than it deserves.
The next article is of the same nature; I mean, something of a mystery
in trade; and therefore to be touched very gently. What I would hint
is, that it is the opinion of many very intelligent persons, that a
good deal of malt is made, which does not pay the excise. I do not
pretend to ascertain the quantity: perhaps one eighth may not be an
extravagant supposition. And if this be the case, we shall find as much
barley, as will weigh against bread for half a million of people.
But here, in all probability, you will object, that if all these
articles be admitted, we shall make the number of people near eleven
millions; which is undoubtedly too much. I am ready to grant it. And
here, if I might take the liberty to speak my mind, I think, that the
allowance of one quarter of wheat to three persons is too scanty,
and must quite starve the poor, whose chief provision is bread: and
therefore, two persons to a quarter may be pretty near the truth. And
then the numbers will stand thus:
Such as eat wheat, by supposition 4,500,000
In the North, and in Wales 1,500,000
Against the fatting article 1,000,000
Against the two last articles 1,000,000
---------
8,000,000
I cannot conclude this long scroll without recommending it strongly
to the members of the Royal Society, who have many of them seats in
parliament, and most of them interest in those that have, to get an
Act passed for perfecting registers. The trouble is trifling; the
expence nothing. It would be of great service likewise to number the
people: and this might be done with great ease. I was not three hours
in finishing mine on foot; tho’ it is, perhaps, as extensive, for the
number of people, as most in England, being near five miles in length.
I am,
Reverend Sir,
Your affectionate Brother,
and very humble Servant,
Richard Forster, _Rector_.
XLIV. _A remarkable Case of an Aneurism, or Disease of the principal
Artery of the Thigh, occasioned by a Fall. To which is prefixed a short
Account of the Uncertainty of the distinguishing Symptoms of this
Disease. By_ Jos. Warner, _F.R.S. and Surgeon to_ Guy’s Hospital.
[Read Nov. 17, 1757.]
WHEN the coats of an artery become by any means præternaturally
distended, when they become wounded, or when they become ruptured in
such a manner as to discharge and deposit their former contents under
the neighbouring integuments, under the aponeurosis, or tendinous
expansion of a neighbouring muscle, or still more deeply under the
muscles themselves; the natural consequence attending this accident
will sooner or later be a degree of elevation, or tumor: which species
of tumor is known by the term _aneurism_.
If a true aneurism happens, that is, a swelling arising from a general
weakness of the coats of an arterial vessel, or from a wound or rupture
of some of its coats, it may be often distinguished from a tumor
proceeding from any other cause by a degree of pulsation, supposing
the situation of the injured vessel be superficial; as may be evinced
in recent aneurisms of the humeral artery, which sometimes happen from
bleeding near the bending of the elbow-joint; as well as in aneurisms
of the inferior part of the radical artery, of the ulnary artery, or
of the anterior artery of the leg called _tibialis antica_; and as
may be observed to be sometimes the case too in those arteries, whose
situations are not superficial; to wit, in aneurisms of the _aorta
ascendens_, the curvature of the _aorta_, and of the _carotides_.
The symptom of pulsation in tumors, which take their rise from a
partial wound, or from a general weakness, and subsequent dilatation of
the coats of an artery, is not confined to this species of aneurism,
but is frequently attendant upon false aneurisms (that is, such
tumors, as are occasioned by extravasated arterial blood), supposing
the disease to be a recent one of either of the preceding vessels, or
of any other arterial vessel not deeply situated: and this symptom
of pulsation in false aneurisms will sometimes be accompanied with a
discoloration, or variegated appearance, of the integuments dependent
upon the insinuation of the blood underneath them.
But if the extravasation be confined under an aponeurosis, or if the
disease has been of so long standing, as to admit of the thinner
parts of the extravasated blood being absorbed, or by any other means
dispersed, and the fibrous parts, which are left behind, should be
accumulated in considerable quantities, and acquire so compact and
solid an appearance, as to resemble brown macerated leather in their
colour and texture, which I have always observed to be the case in old
diseases of this kind; under these circumstances, the original symptoms
of pulsation on the swelling, and a discoloration of the integuments,
for the most part become imperceptible: for which reasons the true
nature of the disease must be attended with a degree of uncertainty.
It must be acknowleged by all those, whose experience has given them
opportunities of examining into these diseases, that the symptoms of
a pulsation, and a discoloration of the teguments from extravasated
blood, are not only very often wanting in old aneurisms, but in the
most recent ones: which proves the non-existence of these symptoms to
be no certain characteristics of tumors not being aneurismal: and the
reason why this often happens may be readily explained, and conceived
of, from demonstrating the very deep or low situation of many arteries,
that are known to be liable to these injuries; such as the femoral
arteries, the _arteriæ tibiales posticæ_, the _arteriæ peroneæ_, and
some others.
Notwithstanding I have treated of pulsation on tumors, and a
discoloration of the integuments or coverings of the part, when they
do exist, as being the truest marks of aneurisms; yet it must not be
inferred from what has hitherto been advanced, that the appearances of
these symptoms are unexceptionable rules of tumors being aneurismal;
seeing it does happen, that mere imposthumations, or collections
of matter, arising from external as well as from internal causes,
are sometimes so immediately situated upon the heart itself, and at
other times upon some of its principal arteries, as to partake in the
most regular manner of their contraction and dilatation (systole and
diastole).
Some years ago I saw an instance of a boy, about 13 years of age,
who had his breast-bone much broken by a fall. On this account he
was admitted into Guy’s Hospital; but not till a fortnight after the
accident happened.
Upon examination, there appeared an evident separation of the broken
parts of the bone, which were removed at a considerable distance
from each other: the intermediate space was occupied by a tumor of a
considerable size: the integuments were of their natural complexion:
the tumor had as regular a contraction and dilatation as the heart
itself, or the aorta could be supposed to have.
Upon pressure, the tumor receded; upon a removal of the pressure, the
tumor immediately resumed its former size and shape. All these are
the distinguishing signs of a true recent aneurism. The situation
and symptoms of this swelling were judged sufficient reasons for
considering the nature of the disease as uncertain; on which account
it was left to take its own course. The event was, the tumor burst in
three weeks after his admittance, discharged a considerable quantity of
matter, and the patient did well.
From what has been above advanced it is plain, if these arguments can
be supported by facts, that the laying down such rules for infallibly
distinguishing aneurismal tumors from tumors proceeding from very
different causes, must be a matter of the greatest difficulty: and, as
a further proof of their uncertainty, I take the liberty of offering
the following short history of a remarkable case, which has lately
occurred in my own experience.
In the month of December 1756. John Yates, aged 35 years, received an
hurt upon and about his knee, by falling upon the ground from a man’s
back. The accident was immediately followed with a considerable degree
of lameness and pain; which upon standing or walking were greatly
increased.
He continued in much the same state for about six weeks after the
accident. At the end of this time, the calf or the leg was attacked
with an œdematous or doughy swelling; which, in a fortnight, became
so painful, as to disable him from walking. The tumor continued to
increase for about eight weeks; and at length extended itself so far
upwards, as to affect the greatest part of the thigh, the whole of
which was attended with excessive pain, but more particularly so about
the knee.
_N. B._ So far I relate from the patient’s own account.
On the 28th of April 1757. he was admitted into Guy’s Hospital under my
care.
Upon examination, the thigh appeared enlarged to a very great size. The
tumor was uniform, and extended from the inside of the knee to within
a very small space of the groin. The integuments were in every part of
their natural colour.
Upon pressing the tumor on the inside, it appeared soft, and there was
a very evident fluctuation to be felt on its internal and lateral part;
but there was not the least appearance of pulsation.
The tumor, on its superior and posterior parts, was of a stony hardness.
The leg, which, according to the patient’s account, had some time ago
been much swelled, did not now appear to be at all so.
He was continually in great pain, and had been for some time incapable
of getting any sleep. His appetite was bad. He was a good deal
emaciated. He had a constant slow fever, which arose about five weeks
before his admission into the hospital. He appeared pale and sallow in
his complexion.
From the time of his being placed under my care to the end of ten days,
there was no alteration in the swelling, or in the symptoms attending
it.
In expectation therefore of affording him that relief, which could by
no other means be procured, I judged it adviseable to make an opening
into the tumor; which I did by incision into the most prominent and
fluctuating part; upon which there immediately gushed out a large
stream of thin florid blood, and at this instant discovered to me the
true state of that disease; which, till now, could not be ascertained
by any peculiar symptom distinguishable by the touch, or perceptible to
the eye.
Seeing this, I immediately filled up the wound with lint and tow; and
then proceeded, in as expeditious a manner as possible, to apply a
tight bandage upon the thigh, near to the groin; and, lest this might
accidentally break, I applied a second ligature below the first, and
proceeded to amputate the limb upon the spot.
During the operation the man fainted, but soon recovered from this
deliquium; and, without any bad symptoms, gradually recovered his rest,
appetite, and strength, and is now in perfect health.
Upon a dissection of the thigh and leg, I discovered the following
appearances:
A great part of the fleshy portions of two of the extensor muscles of
the leg, to wit, the _vastus internus_, and _crureus_, were destroyed,
with the subjacent _periosteum_.
Four of the muscles, whose uses are to bend the leg, and which
compose the internal and external hamstrings; to wit, _gracilis_,
_semitendinosus_, _semimembranosus_, and _biceps tibiæ_, together
with that adductor and flexor muscle of the leg called _sartorius_,
were removed at a considerable distance from the thigh-bone on its
inferior part, and from the _tibia_ and _fibula_ on their superior
parts; by which means a large bed or cavity was formed for containing
the extravasation, which consisted partly of a fluid, and partly of
a coagulated blood; but by far the greatest part of the coagulum had
acquired so firm and fibrous a consistence and appearance, as nearly
to resemble brown macerated leather in its colour and texture. The
neighbouring muscles appeared livid and lacerated.
The _os femoris_ was become carious on its inferior and posterior
parts; and, at about an inch distance above the condyle of that bone
internally, there arose a considerable _exostosis_.
The capsular ligament of the knee-joint was become much thickened, and
contained about two ounces of a viscid yellow _synovia_.
The femoral artery, on its inferior part, just above its division into
_tibialis antica_ and _postica_, was diseased; which disease extended
four inches upwards.
The coats of the artery were considerably thickened, and lacerated
longitudinally.
The smallest diameter of the diseased part of the artery was two inches
and one quarter: the largest diameter of the diseased part of the
artery was two inches and one half.
Hatton-Garden,
Nov. 17. 1757.
XLV. _Farther Experiments for increasing the Quantity of Steam in a
Fire-Engine. By_ Keane Fitz-Gerald, _Esq; F.R.S._
[Read Nov. 24, 1757.]
I Gave a former account to the Royal Society of some experiments made
for increasing the quantity of steam in a fire-engine, by blowing air
thro’ boiling water[199]. The effects then evidently produced left me,
and I believe many others, who came to view the experiments, no room to
doubt the seeming cause. In which error I should probably have still
remained, had not farther experiments demonstrated the mistake.
Whatever apology I ought to make this learned Society, for having given
in that account prematurely, I believe their great regard to truth,
which has always been the basis of their researches for the improvement
of natural knowlege, will require none for this. I shall therefore, as
briefly as I can, relate the further experiments, that were made, which
evidently demonstrate the error of the former; and from which some
phænomena have occurred, perhaps hitherto unknown.
In order to try what difference the air passing thro’ a thinner body
of water might occasion, I brought the horizontal pipe, which (as
mentioned in the former account) was placed 12 inches under the surface
of the water, to within six inches; and found, on setting the engine to
work, that the leaden pipe, for the conveyance of air from the bellows
into the boiler, became much hotter than I had perceived it before;
which could not happen, if a constant cool air had passed thro’: and
on shutting the cock, which was fixed in the leaden pipe to hinder the
steam from ascending into the bellows before the engine should be set
to work, tho’ no air could then possibly pass thro’, yet the bellows
still continued to move with the same regularity as before; which, on
examination, was found defective on the inside, where the middle board,
that divides the two bodies, was warped and cracked in several places,
thro’ which the air passed very regularly from one body to the other
at each stroke, instead of passing thro’ the pipe into the boiler, as
imagined. By this, the cause of deception was evident; which I was
still in hopes of remedying, by having a new pair of bellows made,
somewhat larger, and much stronger. When this was fixed, and the engine
worked a few strokes, I was surprised to find the bellows did not come
down, but remained fully charged with air, tho’ it had 400 lb. weight
upon it; and that, on increasing the weight gradually to 1400 lb. which
was as much as the bellows could support, the air was not forced thro’.
I also made several experiments, by lowering the horizontal pipe two
feet under the surface of the water, and raising it at different times
to within four inches of the surface, and could not at any depth force
the air thro’, whilst the engine worked; but on opening the steam-pipe,
which is a pipe for letting the steam pass from the boiler whenever
the engine stops, the bellows could then readily force the air thro’,
tho’ the water boiled ever so strong, and seemingly made a surprising
increase of steam.
I had the leaden pipe to convey the air from the bellows, which was
first put thro’ the top into the boiler, carried on the outside, and
passed horizontally into it, about the height the water generally
stands, that by opening a cock, fixed for the purpose close to the
boiler, I could readily discharge all the steam lodged in the pipe; and
by shutting the cock, and making small holes at three or four inches
distance, I could almost find the point, where the air and steam met in
opposition, cool air being strongly expelled thro’ one, and hot steam
thro’ the other.
It was also perceptible, that the air was impelled somewhat, tho’ not
considerably, more forward by the addition of each hundred weight on
the bellows:
That the deeper the horizontal pipe was placed in the water, the less
resistance was made by the steam:
That in proportion as the heat of the steam was increased, by making
the water boil more strongly, the resistance to the pressure of the air
by the weight on the bellows became greater.
It is a very doubtful matter, whether air forced thro’ boiling water
would have answered the purpose intended: but I believe it was never
imagined, that air could not be readily forced thro’, until proved by
the foregoing experiments. The attempt, tho’ it has failed demonstrably
in that point, has produced the same effect from another cause, as to
saving coals, and throwing up more water. For, by the constant care,
that was taken during the time of making these experiments, to measure
the coals, to admit only a proper quantity of fuel to be laid on, and
also to mark the time exactly it took in burning; the engine then did,
and still continues to require eight bushels of coals less, in every 24
hours work, than it did before; and also, from the regularity of its
stroke, to throw up more water; the same care being required from the
engineer, who can have no pretence for consuming more coals now, than
appeared sufficient during the time the experiments were making.
Tho’ some of the properties of steam are well known; yet the degrees of
expansion it is capable of; whether air be mixed with, or necessary
to, its formation; as also how far its power of resistance may reach;
are probably not yet known, to a proper degree of exactness. Niewentit
fixes the expansion of a cubical inch of water, converted into steam,
at 13365, Dr. Desaguliers at 14000, and Mr. Payne at 4000 times. The
great scope in this subject from a plenum to a vacuum, if I may be
allowed the expression, as also the very useful purposes, to which it
has already been, and possibly may be still further applied, will, I
hope, be an inducement to those, who are much better qualified, to
proceed in so useful an inquiry.
XLVI. _Observatio Eclipsis Lunæ Die 27_ Martii, _Ann. 1755. habita
Ulissipone in Domo Patrum Congregationis Oratorii à_ Joanne Chevalier
_ejusdem Congregationis Presbytero, Regiæ_ Londinensis _Societatis
Socio, Regiæque_ Parisiensis _Scientiarum Academiæ correspondente_.
Tubo optico 8 pedum peracta est observatio cœlo sereno, claroque.
[Read Dec. 8, 1757.]