HOW SCIENCE HELPS TO KEEP US WELL
One branch of science--medical science--concerns itself almost entirely
with health, but it would be out of place to refer to such matters here,
even if the present writer were capable of doing justice to the subject.
A new medicine or a new method of operating upon a suffering patient
would be quite correctly described as a scientific marvel, but it is not
of such that this chapter deals, but rather with those great works by
which the engineer, often taught by the medical man, promotes the health
of a whole community.
Most important of these, perhaps, is the provision of pure water. Some
places are more fortunately situated than others in this respect, being
near streams flowing down from mountains clear and unpolluted, which can
be drunk after the minimum of purification. Others have to make use of
the waters of a moderately clean river, as London does those of the
Thames and Lea, in which cases the greatest care has to be exercised in
the filtration of the liquid before it can be sent out through the mains
for domestic consumption.
In this particular domain invention has been comparatively slow. There
are novel pumps, it is true, for handling the water, such as the
Humphrey Gas Pump, which the Metropolitan Water Board (London) have
installed for filling their great reservoirs at Chingford. In these an
explosion of gas is the motive force. Water flows by gravitation into a
huge iron pipe closed at the top but open at the bottom. It is so
arranged that a quantity of gas shall be entrapped in the upper end,
which, being exploded by an electric spark, drives the mass of water
out. Some of it, together with a quantity of fresh water, presently
comes surging back, entrapping a fresh supply of gas and causing a new
explosion; and so it goes on over and over again. The particular pumps
at the waterworks referred to discharge about fourteen tons of water at
each explosion, of which there are nine every minute.
The special effect of these machines, however, is not to improve the
public health so much as to relieve the public pocket, for their chief
feature is that they work more economically than any other kind of pump.
The filters, by which the water is purified, are simply layers of sand,
much the same as have been in use for many years, although in some cases
chemistry is brought in and the work of the filters aided by the action
of precipitants. These are substances which combine in some way with the
impurities in the water, and carry them to the bottom of the tank or
reservoir, while the pure water remains to be drawn off from the top.
This is also the most usual method by which water is softened. Hardness
in water is due to the presence of certain salts which are dissolved out
of the ground as the water percolates through it, and which are absent
from rain-water. To get rid of these the hard water has chemicals mixed
with it in a tank, from which it flows slowly through another tank. The
effect of the added chemicals is to convert the soluble salts in the
water into insoluble particles, which then tend to fall down to the
bottom of the containing vessel. The slow passage through the second
tank is intended to give the particles time to settle.
[Illustration: SECTIONAL VIEW OF HYDRAULIC BUFFER AND RUNNING-OUT
PRESSES OF A 60-POUNDER GUN]
Finally, to make sure that these have been all got rid of, the water
traverses a filter, and then it is for all practical purposes as soft as
rain-water. Some people are frightened of this artificially softened
water, on the ground that chemicals have been added to it, supposing,
apparently, that when they use such water they are really employing a
chemical solution. That is quite wrong, however, for the added
chemicals, combining with the "hardness," form substances which are
quite easily extracted from the water altogether. If we liken the
hardness to a number of pickpockets in a crowd, and the added chemicals
to a number of policemen who come in to arrest the said pickpockets,
finally leaving the crowd free from both pickpockets and policemen, we
get a simple illustration of what takes place.
But almost equally important as the provision of pure water is the
effective dealing with the drainage of a large town. Much offensive
matter flows under the streets of our towns and cities, and if it is not
to become a nuisance it must be scientifically dealt with.
Years ago the drains of London simply emptied themselves into the
Thames, until, in 1864, two large drains were constructed, one on each
side of, and approximately parallel with, the river, to intercept the
old drains and to carry their contents to points many miles down towards
the sea. Even that, however, by no means abated the evil, for it simply
transferred it to a new place. The river was as foul as ever.
William Morris, in _News from Nowhere_, pictures the catching of salmon
in the Thames off Chelsea, while one of London's prominent citizens,
referring to what was being done in the direction of purifying the
river, jocosely promised the members of Parliament a little fly-fishing
at Westminster. Equally remote, it is to be feared, from actual
accomplishment, these two prophecies do certainly indicate the tendency
of events, for science has enabled the authorities to relieve the
long-suffering river of much of the pollution which they used to thrust
into it.
The first great step was the introduction, in 1887, of a treatment in
principle very like that just described for softening water. The liquid
from the drains is gathered into large reservoirs, where chemicals are
added to it, causing the heavier matter to be precipitated in the form
known as "sludge."
The liquid portion, or "effluent," as it is called, which is left is
discharged into the river just as the tide is ebbing, so that it is
carried right away, and, being comparatively inoffensive, it pollutes
the river very little indeed. The sludge, on the other hand, is pumped
into special steamers, which carry it down to a certain spot off the
Thames Estuary, where they drop it into the sea. The currents at the
particular spot chosen are such that none of it returns to the river.
For a similar purpose electrolysis has been employed. In this process
the sewage is made to flow between two iron plates which are connected
up to a source of electric current so that they form electrodes, while
the sewage is the electrolyte. The current decomposes the liquid sewage,
causing chlorine and oxygen to be deposited upon that plate which forms
the anode. This deodorises and purifies the sewage, in addition to which
iron salts are formed on the iron plates, the effect of which is to
precipitate the solid particles. Thus the same result is achieved as
when chemicals are used, the main difference being that instead of
chemicals being added, they are produced by the passage of the current.
But, from the scientific point of view, the most interesting process of
all is that in which bacteria or microbes are brought into the service.
The fact is familiar to most people that there are certain minute
organisms which cause terrible diseases. It is not so well known that
there are still more of them whose action is extremely beneficent. The
writer has seen these minute living things described in a popular book
as "insects," but they really belong to a low order of plant life, and,
as has been said in an earlier chapter, in spite of the lowliness of
their status in the order of creation, they are able to accomplish
certain chemical processes which baffle the cleverest men. They are
particularly good, or some of them are at any rate, at forming compounds
in which nitrogen forms a part. Further, they can be divided into two
classes, the aerobic and the anaerobic. The former work best in air,
while the latter need an absence of air while they perform their
functions. After which preliminary explanation we can proceed to
describe how they are induced to carry on this valuable work for
mankind.
The sewage flows first of all into a tank from which light and air are
excluded as far as possible. There the anaerobic microbes flourish and
multiply, and in the course of their life work they convert the sewage
into an inoffensive liquid. After an appropriate interval the liquid
passes to filter-beds, where it trickles over and through beds of coke,
the effect of which is to aerate it very thoroughly, whereby the aerobic
microbes come into action, completing the good work, so that nothing is
left except a clean, colourless and odourless liquid. Indeed it is more
than that, for the microbes have turned the offensive matter into
nitrogenous compounds which, as we have seen in a previous chapter, are
the best fertilisers. Hence this effluent, if placed upon the soil, is
of great value.
The advantage of this to towns which are not blessed, like London, with
a broad river and the sea near at hand needs no explanation.
The bacteria necessary to carry on the process are always present in
sewage, and after any particular plant has been in operation for a
little while there results an accumulation of them, so that the process
becomes more and more active as time goes on. Mechanical ingenuity has
so arranged matters that a sewage disposal plant on this system can be
made quite automatic, requiring little or no attention for months
together, the raw sewage flowing in at one end, while the odourless,
harmless effluent pours out at the other.
And, moreover, so powerful is the action of these beneficent bacteria
that should disease germs come down in the sewage they soon destroy
them. No chemicals are needed, for the bacteria replenish themselves. No
sludge is left, everything being turned into the harmless effluent. And,
it may be said once more, disease germs are destroyed. Of all the
valuable inventions of modern times this is surely not one of the
least.
CHAPTER XIX
MODERN ARTILLERY
Even as late as the time of the Crimean War guns, even the largest, were
made of that extremely common material, cast-iron. In fact, so far as
material went, there was no difference between a gun and a water-pipe.
It was the need for some material possessing strength comparable with
that of steel combined with the ease of production of cast-iron which
led Sir Henry Bessemer to experiment in the manufacture of steel. Out of
those experiments came Bessemer steel and its near relative, Siemens
steel, two materials of universal application at the present time, so
that to the needs of the artilleryman we owe two inventions which have
proved of infinite value in peace as well as in war.
If any particular piece of ordnance can be said to be the prime
favourite with the English-speaking peoples, it is the big naval gun.
With both British and Americans the navy takes pride of place; both
nations are given to contemplating with pleasure the number of
dreadnoughts which they possess, and the distinguishing feature of a
dreadnought is the large number of big guns which it carries.
Of the latest of these gigantic weapons one may not speak, but much is
already public property concerning the 12-inch gun which the original
_Dreadnought_ carried, and which is probably followed in its general
features by the still greater guns of the most recent ships.
A gun is spoken of by its "calibre," which means the inside diameter,
or, to use another expression, the size of the "bore." So the "12-inch"
naval gun is 12 inches in the bore. Its length is in some cases 45
calibres and in others 50 calibres. In other words, some are 45 feet
long and others 50 feet.
Why the difference? someone may ask. The answer is that the longer ones
are an improved type. The extra length gives longer range and harder
hits, as is quite apparent after a little thought. The explosive "goes
off" and forthwith commences to drive the shell towards the muzzle. So
long as it is in the gun the shell is being pushed faster and faster,
but so soon as it leaves the muzzle the pushing ceases and the shell is
left to pursue its course with its own momentum. Therefore, generally
speaking, one may say that the longer the gun the faster will be the
speed of the shell as it leaves the muzzle, the farther will it go and
the harder will be the blow at a given range.
Incidentally this explanation reveals the need for different kinds of
explosive. The propellant whose function it is to drive the shell out of
the gun is different from that with which the shell is itself filled.
The former needs to act comparatively slowly, so that it may continue
its pushing action during the whole time that the shell is travelling
along the gun. It might be ever so powerful, but were its action too
sudden it would simply tend to burst the gun, without imparting very
much speed to the shell. On arrival at its destination, however, the
shell needs to burst suddenly and violently.
Another interesting question arises at this point. Seeing how fast is
even the slowest speed at which a projectile travels, how can it be
possible to measure the rate at which a shell issues from one of these
monster guns. Needless to say, it is electricity which makes a thing
apparently so difficult really quite easy.
Near the gun is set up a frame with a wire zigzagging to and fro across
it, in such a manner that when the gun is fired the shell is bound to
cut the wire. Electric current is made to pass through this wire on its
way to a suitable house in which are recording instruments, where it
energises a magnet and so holds something up. Now it is easy to see
that as soon as the shell cuts the wire the current will stop, the
magnet will "let go" and the "something" will drop.
At a certain distance farther on there is a second frame with wires upon
it, through which passes a second current, which is also led to the
instrument house, where it again operates a second magnet.
When the first magnet releases its hold it drops something, to wit, a
long lead weight. When the second magnet lets go it permits a second
weight to fall against the first and make a dent or scratch upon it. The
longer the interval between the action of the two magnets the higher up
upon the lead weight will the scratch be. The apparatus, in short, will
register the distance fallen through by the lead weight between the
breaking of the wire in the first frame and the breaking of the wire in
the second frame.
Now a falling object, if only it has such weight that the resistance of
the air is negligible, falls according to a well-understood law, which
law it obeys with the utmost accuracy. Therefore the distance fallen by
the weight between the passage of the shell through two points gives a
very accurate record of the time taken to travel from one to the other.
Of course several such frames can be used if desired in the same way.
But to return to the gun itself. It is not merely one piece of metal but
several tubes beautifully fitted one inside another. Moreover, in the
British gun at all events, between two of the tubes there is a space
filled with "wire."
This wire is perhaps better described as steel tape, and is of the
finest material for the purpose, flexible and tremendously strong. It is
wound round and round one of the tubes until there are many miles of it
on a single gun. It is wound tightly, too, by means of special
machinery.
The purpose of the wire is to resist cracking. The solid steel tubes may
crack, and, as is the way with all cracks, these will tend to grow
longer and longer. The many turns of wire, however, will not crack. Even
if a few turns should break, the damage will not spread, and the gun
can probably go on as if nothing had happened.
The material of which these guns are made is nickel chrome gun steel.
Steel is ordinarily an alloy of iron and carbon, but this metal also
contains traces of nickel and chromium, which make it specially suitable
for its special purpose.
Each of the tubes of which the gun is formed start as an ingot, a mere
lump of metal, but roughly shaped. The requisite mixture is obtained in
a furnace and the molten metal is run out into a mould. The ingot is
heated again and pressed under enormous hydraulic presses until it is
approximately the shape required. This pressing not only produces the
desired shape, it also improves the quality of the metal.
The rough forging is then bored out, to make it into a tube. One is
inclined to wonder why the ingot is not cast hollow to commence with,
and so save the labour of boring it all out later. The explanation of
this is that certain impurities are always present in the metal and
these always gather together in the part which sets last. Now in a solid
block or ingot it is clear that the centre is the part which will set
last, and hence that is the part where the impurities will congregate.
Then, when the centre part is all bored out the impurities are entirely
removed.
The tube is shaped externally by being turned in a lathe.
The innermost tube is not simply smooth. There is a spiral groove,
called the "rifling," running round and round, screw fashion, inside it.
The purpose of this is to give the shell a spinning action which causes
it to keep point foremost throughout its flight. But for this the shell
would tend to turn over and over, resulting in uncertain and inaccurate
flight.
The shell is a little smaller than the bore of the gun, but near its
base it has an encircling band of soft copper, which band is a tight fit
in the gun. The soft copper crushes into the "rifling," whereby the
shell obtains its spinning action.
The large guns are mounted in pairs, each pair on a turntable, by the
movement of which to right or left they are trained upon the distant
target. The turntable is surrounded by a wall of thick armour and is
covered by an iron hood or roof.
In addition to being turnable to right or left, there is, of course,
provision for raising or depressing the direction in which each gun is
pointing. They need always to point more or less upwards, and the
particular angle depends upon the range or distance of the object aimed
at. This is ascertained by range-finding instruments and communicated to
the officers in the turrets, as the covered turntables are called. The
guns are then elevated or depressed to suit the range.
Each gun rests upon a cradle which is itself fitted upon a slide. When
it is fired it "kicks" backwards, against the force of a buffer of
springs, or a hydraulic or pneumatic cylinder. Thus after each shot the
gun moves backwards upon the slide, but the hydraulic apparatus brings
it back again into position for firing almost instantaneously.
In naval guns all the movements, including that of the turntable, are by
power, either hydraulic or electric, or a combination of the two. The
loading is also by power.
The shells and ammunition are kept well down towards the bottom of the
ship, under each turret. Lifts bring them up from there to a chamber
just beneath the turntable, known as the working chamber. Here a small
quantity only is kept, and that for as short a time as possible before
it is sent up by other hoists straight to the guns themselves. The
hoists are so arranged that, no matter how they may be elevated or
depressed, the ammunition is delivered exactly opposite the breech, as
the rear end of a gun is termed. Then a mechanical rammer pushes it
straight in.
[Illustration: RIFLES OF DIFFERENT NATIONS
(_See_ Appendix)]
The breech of the gun is closed by a beautiful piece of mechanism called
the breech-block. It is really a huge plug which securely closes the end
of the gun, a partial turn after it is in place fixing it firmly enough
to resist all the force of the explosion. Yet it can be freed and
swung back upon hinges in a few seconds. At the same moment that it is
opened a jet of air blows into the gun, clearing out all effects of the
recent explosion.
The process of firing one of these guns may thus be summarised. The
turntable is swivelled to right or left until the gunners, looking
through the sights, which are really telescopes, see the object straight
in front of them. Meanwhile the sights have been set according to the
range--that is to say, they have been so set in relation to the gun
itself that when they point directly at the target the gun will be
pointed upwards at exactly the right angle for that range. The whole
thing, therefore, gun and sights combined, is tilted upwards or
downwards as may be necessary until the sights point directly at the
object aimed at. Then at a signal the gun is fired by electricity. The
shock causes the gun to slide backwards upon its supporting slide, but
the buffers, having taken the shock automatically, return it to its
position again; the aim is thus undisturbed and it is ready for the next
shot. These enormous guns can be fired at the rate of one shot every
fifteen seconds.
Field guns are in principle very similar to these, only, of course, they
are much smaller and are mounted upon carriages, so that they can be
quickly moved from place to place. It must be borne in mind, however,
that there are in the case of land guns two distinct types. Field guns,
like naval guns, fire straight at their target; howitzers or mortars
fire upwards with a view to letting the shell fall on the target from
above. The latter are, generally speaking, short, fat, stumpy guns, as
compared with the long, slender field guns.
In the field all guns have to be loaded by hand. The elaborate system of
hoists which enables the great naval guns to be loaded with such
rapidity is obviously impossible. That has to be compensated for by the
skill and quickness of the gunners themselves, and it is indeed
astonishing to see with what deftness they can handle the heavy and
dangerous projectiles.
With all guns, of whatever kind, range-finding is of the utmost
importance. No projectile, however fast it may travel, really moves in a
straight line. It must be fired more or less upwards in order to
compensate for the downward pull of gravity. If the elevation be
insufficient the shell will fall short; if it be too much it may go
beyond the mark, or it may fall short, according to circumstances. Just
the right elevation is absolutely essential for good shooting. And for
that to be achieved the range must be known with the utmost possible
accuracy.
There are various systems and instruments used for this purpose, but all
depend upon the same principle. It is the principle underlying all
surveying and all astronomy; indeed it is the only possible principle
for measuring a distance when you cannot actually go and lay a measure
upon it or by it.
It is based upon a peculiar property of a triangle. In the case of every
triangle which has straight sides, if we know the size of two of the
angles and the length of one of the sides we can easily calculate all
that there is to be known about that triangle. We unconsciously use the
principle when we judge a distance with our eyes. We focus each eye
separately upon the object which we are looking at. In other words, each
of our eyes looks along a straight line terminating in the object. Those
two lines, together with a line joining our two eyes, form a triangle.
The line between our eyes is the "base," the line of which we know the
length, while the directions in which we point our eyes give us the
angles at each end of the base. From this we are able to judge the
distance of the object. Of course there is probably not one of us who
knows the length of that natural "base" in inches, but that does not
matter in this case, since it is always the same whatever we may look
at, and so the mere inclination of the eyes gives us a means of
comparing distances. When we judge by the eye alone, what we really do
is to draw upon our experience and consciously or unconsciously compare
the distance which we are estimating with some others which we already
know.
In surveying, a telescope is set up at one end of a base-line and
pointed first at the other end of the base-line and then at the distant
object. A scale with which the instrument is provided gives us the size
of the angle between the two. Then the same thing is done at the other
end of the "base" and the similar angle there is obtained. The length of
the base being known, the distance of the remote object can then be
calculated.
In the same way two observations can be made, one at each end of a ship,
the length of the ship forming the base-line. Or an instrument can be
made by which two observations can be made simultaneously by the same
man.
This is done by means of mirrors which are turned so that the same
object is seen in both of them, apparently in a straight line. The
extent to which one of them has to be turned gives the angle, and the
instrument forms the base.
Anyone with the slightest geometrical experience will perceive at once
that the best results are obtained when the base-line is of considerable
length, and hence small portable range-finding instruments such as can
be easily carried and used by one man are necessarily less accurate than
an arrangement such as has been suggested above, where two observers
work simultaneously from the two ends of a ship.
In many cases, however, the self-contained instrument is the only one
which it is possible to use, and when the instrument is well made and in
experienced hands the results are surprisingly good.
As used in surveying, for example, where the base-line may be anything,
according to circumstances, and the angles may likewise vary at both
ends, elaborate trigonometrical calculations have to be performed to
arrive at the desired result. If, however, the base-line be always the
same, and one of the angles be always a right angle, the distance of the
distant object will vary with the remaining angle. Indeed the scale by
which that angle is measured can be made to give not degrees, but the
distance of the object. Portable range-finders, therefore, in many cases
have one reflector set for a right angle and only one of the reflectors
movable. The instrument then shows the distance of the object at a
glance.
This is impossible in the case of two separate observations on a ship.
In that case the base is always the same, but since the ship cannot be
set at right angles to the object whenever a range has to be found, both
angles have to be measured. There is, however, a beautifully simple
little mechanism in which two pointers are set one to each of the two
angles, and the distance is then shown instantly.
APPENDIX
A DESCRIPTION OF THE RIFLES SHOWN AT PAGE 240
THE GERMAN MAUSER can fire forty rounds a minute--more than any other
rifle used in the war. The rifle is of the 1898 pattern, weighs 9 lb. 14
oz. with bayonet fixed, and is sighted from 219 to 2187 yards. The
magazine holds five cartridges, packed in chargers. As the rifle is not
provided with a cut-off, it cannot be used as a single-loader. With its
long barrel and long bayonet it gives a stabbing length of 5 ft. 9
in.--8 in. longer than the British.
THE AUSTRIAN RIFLE is the Mannlicher. This rifle is very fast in action
as a snap back and forth of the wrist is sufficient to operate it. It
is, however, more trying for prolonged work, owing to the throwing of
the strain only on the wrist. Without the bayonet the rifle weighs only
8 lb. 5 oz., the lightest of all, yet the bullet--244 grains--is the
heaviest used by any of the belligerents. The rifle is sighted from 410
to 2132 yards, and the barrel has a four-groove rifling.
THE BRITISH LEE-ENFIELD--MARK III--is the outcome of the South African
War. It is not too long for horseback and is yet quite efficient for
infantry. The barrel is 25 in. long and has five grooves in the rifling.
It is sighted from 200 to 2800 yards. The rifle is fitted with a
magazine which holds ten cartridges packed in chargers, each of which
contains five rounds, so that the magazine is filled with ten rounds in
two motions. The rifle is also fitted with a cut-off, which enables it
to be used as a single-loader. It is altogether a most efficient
weapon.
THE FRENCH LEBEL is of the 1886-1893 pattern, and with bayonet fixed is
longer than any other rifle. It weighs, without bayonet, 9 lb. 3-1/2 oz.
The tube magazine under the barrel contains eight cartridges; it takes,
of course, longer to charge than a magazine loaded with a charger. It
does not fire as many shots a minute as some of the other rifles in the
field. The position of the magazine is indicated by the crosses. The
rifle is sighted from 273 to 2187 yards, and the bullet weighs 198
grains.
THE BELGIAN ARMY uses the 1889 pattern Mauser, which weighs just over 8
lb. and is sighted from 547 to 2187 yards. The magazine holds five
cartridges carried in clips; not having a cut-off, the rifle cannot be
used as a single-loader. It has four grooves in its rifling and measures
4 ft. 2-1/4 in., or, with the bayonet, 4 ft. 11-3/4 in. The bayonet is
short and flat.
THE "3 LINE" NAGANT of Russia is 1/4 lb. heavier than the British rifle
and is over 7 in. longer. The triangular bayonet is always fixed and
never removed from the rifle. The magazine of the rifle is of the box
type and holds five cartridges. The rifle is capable of discharging
twenty-four bullets to the minute. A useful feature is the interrupter,
which prevents jamming of two cartridges.
THE ITALIAN MANNLICHER-CARCANO is of the 1891 pattern. It weighs,
without bayonet, just over 8 lb. 6 oz. and measures 50-3/4 in. The
barrel, 30-3/4 in. long, has a four-groove rifling. The box magazine,
fixed under receiver without cut-off, holds six cartridges. The magazine
holds six rounds, and the rifle is capable of discharging fifteen rounds
a minute.
INDEX
A
Accumulators or secondary batteries, 65
Aerial craft experiments, 202
Aerobic and Anaerobic bacteria, 234
Afterdamp, 228
Alcohol as a fuel, 49
Alternating current, 35, 193
Altofts, artificial coal mine at, 139
Aluminium, 133
Amalgam, 117
Ammeters, 25
Ammonia in making ice, 72
Ammunition for big guns, 240
Amperes, 22, 24
Analysis and synthesis, 43
Anode, 55
Anschutz, Dr, 96
Antennae, 162, 171
Anthracene oil, 48
Arc, the, in wireless, 165
Argon, the gas, 75
Artesian wells, 45
"Atmosphere," a unit of measure, 72
Atoms, 56
"Avogadro's Constant," 33
B
Bacteria, beneficent, 234
Ball mill, the, 115
Battery, electrical, 23
Benzine, 45, 48
Bessemer, Sir H., 236
Blowpipe, oxyhydrogen, 120
Board of Trade Unit, the, 22
Boiling water, 10, 76
Bore of a gun, 236
Boulders, blasting, 20
Branly, 166
"Brattice cloth," 224
Breech of a big gun, 240
Brennan torpedo, the, 102
Brewing, 50
"Brine" in machine-made cold, 70
"Budding" of yeast, the, 51
C
Calibre of a gun, 236
"Capacity," 153
Capacity and inductance, electrical properties, 161
Carbolic oil, 48
Carbon, 11
Carbonic acid gas, 10
Carburetter, the, 46
Cardiograms, 32
Caselli, 176
Cathode, 55
Cavendish, investigations of, 73
Cellulose, 12, 44
Centrifugal tendency, 115
"Character" of a lighthouse, 86
Charge and current, 32
Cheddite, 13
Chemicals in waterworks, 232
Chemistry, organic and inorganic, 42
Chlorate of potash, 12
Chloride of soda, 58
Chronograph, the, 141
Clark's Cell, 23
Coal and oil, 47
Coal, burnt, 10
Coal-dust an explosive, 10
Coal-dust, explosions from, 139
Coal-pitch, 48
Coal-tar, 48
"Coasting" lights, 80
Coherer, the, 103, 162, 167
Coke in smelting, 125
Colliery explosions, 137
Colliery explosions, rescue apparatus, 226
Colours of the spectrum, 213
Colours of flowers, 213
Compass, a ship's, 91
Compressed air in torpedoes, 100
"Concentrates," 115
Condensers in wireless, 163
Conservation of energy, 132
Contact makers, 145
Coronium, the gas, 74
Corundum, 134
Coulombs, 23
Courrieres colliery disaster, 221
Creosote, 48
Creosote oil, 48
Crooks, Sir W., 33
Crushing mills, 115
Crystal detectors, 171
Curie, M. and Mme., 33
Curtis and Harvey, 9
Cyanide process, the, 118
Cyanogen, 118
Cymogene, 45
D
Detectors, 167
Detonator, the, 14
Dextro-glucose, 51
Diamonds, 135
Diesel engines, 46
Direct-current electric motor, 191
"Dirt-auger," the, 15
Ditches, blasting, 18
Drainage, 233
Du Pont Powder Company, 9
Duddell, W. H., 37
Dufay dioptichrome process, 219
Dynamite, what it is, 9, 12;
in agriculture, 13;
firing a charge, 16;
fruit trees, 16;
marshy ponds, 17;
ditches, 18;
tree stumps, 19;
boulders, 19;
wells, 20
Dynamo, the, 65
E
Eddystone Lighthouse, 80
Edison's accumulator, 66
Einthoven, Prof., 30
Electric arc, the, 123
Electric furnace, 125
Electric fuse, the, 16
"Electrical Inertia," 153
Electrical battery, 23;
pressure, 23;
cells, 23;
measure, 24;
magnetism, 25
Electricity, 22;
the current, 56;
electro-plating, 58;
purification of metals, 61;
secondary batteries, 62
Electrode, 55
Electrolysis, 55, 170;
in drainage, 234
Electrolyte, 55
Electrometer, the, 32, 34
Electro-plating, 58
Electros, 60
Electroscope, the, 34
Endosperm, the, 50
Engines driven by oil fuel, 46
Enzymes, 50
Ether, 45, 149
Ethyl alcohol, 49
Explosions, 9;
in mines, 137
Explosive link, the, 104
Explosives for guns, 237
F
"Falls" in a coal mine, 223
Fermentation, 50
Fessenden, R. A., 169
Field guns, 241
Filters in waterworks, 232
Fire-damp, 137
Firing-pin of torpedo, 102
Flashing lights, 81
Fog, effects of, 82
Fog signals, 88
"Fractional distillation," 76
"Frequency," 36
Frequency meter, 193
Friction clutch, 195
"Frue" vanner, the, 116
Fruit trees and dynamite, 16
Fuses, firing, 20
G
Galvanometer, the, 27, 170
"Gangue," the, 112
Gauges, 208
Gelignite, 12
Glycerine in explosives, 11
Gold, 110
Guiding lights, 81
Gyroscope, the, 93, 100
H
Half-tone illustrations, 181
"Hard-pan," 14
Harris, Sir W. S., 36
_Hawke_ and _Olympic_, collision between, 198
"Head" of the torpedo, 99
Heat and electricity, 37
Heat of the electric arc, 123
Heat, testing by, 205
Helium, 33, 75
Hertz, 154
Howitzers, 241
Hughes, Prof., 159
Humphrey Gas Pump, 231
Hydraulicing, 112
"Hydro-carbons," 45
Hydrogen, liquid, 73
Hydrometer, the, 65
Hydrostatic valve of torpedo, 101
"Hyper-radial" apparatus, 88
I
Ice, machine-made, 71
Indigo, synthetic, 44
Inductance, 154
Induction coil for wireless, 162
Induction furnaces, 129
Insulating ink, 177
"Interference" of light waves, 159
Ionisation of the atmosphere, 172
Iron, 109
J
Jupiter's moons, 150
K
Kelvin, Lord, 28
Kerosene, 46
Kieselguhr, 12
Kilowatt, the, 25
Kinematograph in coal mine experiments, 146
Korn, Prof., 183
Krypton, the gas, 75
L
Leclanche cell, the, 23
Leyden jar, the, 153
Light, speed of, 151
Light waves, 151
Lighthouse, the, 78
Lighthouse lamp, the, 83
Limit gauges, 209
Liquid air, 73
Lodge, Sir O., 159, 161
Lumiere autochrome process, 216
M
Magnetic detector, the first, 168
Magnetic pole, the, 90
Magnetism, 25
Magnets, 25
"Making" light, the, 79
Maltster, the, 50
Mansfield Rescue Station, the, 224
Marconi, 161
Marshy ponds, to remove by dynamite, 17
Mash tun, the, 50
"Master compass," the, 97
"Master" records, 60
Maxwell, J. C., 152
Measuring by electrolysis, 62
Mendeluff's table, 74
Mercury, 114
Metallographic testing, 205
Metals, testing, 204
Methane gas, 10, 124
Methyl alcohol, 49, 53
Microbes, their use, 43
Mine-laying, 105
Mine-sweeping, 107
Molecules, 56
Morris, William, 233
Mud, gold from, 122
Muirhead, Dr, 167
Murette or pedestal of lighthouse lamp, 85
N
Naphtha, 45
National Physical Laboratory, 199
Natural frequency, 161
Neon, the gas, 75
Nickel chrome gun steel, 239
Nitric acid, 11
Nitro-cotton, 12
Nitro-glycerine, 11
Nitrogen gas, 9
Nobel, inventor of dynamite, 12, 135
Nodes, 157
O
Ohm, the, 22, 24
Ohmmeter, the, 27
Ohm's law, 27
Oil, mineral, 44
Oil-producing countries, 47
Optical apparatus of lighthouse, 86
"Orders" of lighthouse apparatus, 88
Ores, 110
Orthochromatic plates, 212
Oscillations, electrical, 36
Oscillatory circuit, 154
Oscillograph, Duddell's, 39
Oxide of iron, 133
Oxyacetylene flame, the, 131
Oxygen gas, 10
Oxyhydrogen jet, 130
P
Paraffin wax, 45
Patents, 174
"Periodicity," 36
"Personal equation," the, 207
Petrol, 45, 52
Petroleum, 44
Phonograph, the, 60
Plans of a ship, 199
Plates of the secondary battery, 64
Platinum, 184
Plumbago in plating, 59
Poulsen arc, the, 173
Poulsen, Valdemar, 165
Pressure gauges, 143
Priestly, investigations of, 73
Primary colours, 213
Prisms, reflection of, 85
Process blocks, 186
Projectiles, velocity of, 237
Propellers of the torpedo, 99
Propellers, testing aerial, 203
Prout's anonymous essay, 74
Prussiate of potash, 177
Purification of metals, 62
Q
Quadrant electrometer, the, 35
Quartz, 113;
fibre, 31, 131
R
Radium, 33
Ramsey, Sir W., 75
Range-finding, 240, 242
Rayleigh, Lord, 74
Receiving instruments for wireless, 162
"Record" vanner, the, 116
"Rectifier," the, 37, 171
Red rays of light, 82
Reflection by prisms, 84
Reflectors, lighthouse, 84
Reiss electrical thermometer, 36
Repeated-impact testing machine, 204
Rescue teams for colliery accidents, 221, 222
Resistance welding, 126
"Resonance," an experiment, 160
Reviving apparatus for coal mines, 229
Rheostat, the, 188, 191
Rhigolene, 45
Rifling of a gun, 239
Rubber, synthetic, 44
Rubies, artificial, 131
Rudders of a torpedo, 100
Rutherford, Prof., 33, 168
S
Saccharine, 48
Saltpetre, 12
Schwartzkopff torpedo, the, 99
Scilly Island lighthouse, 80
Sea, gold in the, 120
Secondary battery, the, 62
"Sectors," 81
Selenium, 184
"Self-rescue" apparatus, a, 228
Shale, oil from, 45
Shells for guns, 239
Ships, testing by models, 200
Short circuit, 179
"Shunt," the, 165
Sighting a big gun, 241
Silica, 133
Skating rinks, ice in, 71
"Sludge" and "effluent" of drainage, 233
Spark detectors, 166
Spark-gap, 162
Spectrum, the, 213
Spinthariscopes, 33
Spirits, 52
Springs, testing, 203
Stamps for crushing quartz, 113
Starch grains in colour photography, 217
"Step-down" and "step-up" transformers, 127
"String galvanometer," the, 30
Submarine mines, 104
Submarine telephone, 88
Sulphuric acid, 11, 43
Sunlight, composition of, 213
Synchronism, difficulties of, 182, 191
Synthetic substances, 44
T
"Tamping," 15
Tank for testing at Teddington, 201;
New York harbour, 201
Telautograph, the, 180
Telectograph, the, 180, 185
Telegraph key for wireless, 162
Telewriter, the, 187
Temperature, measuring, 38
Tesla, Nicola, 164
Testing by heat, 205
Testing machines, 206
Thermit, 135
Thermo-couple, the, 38
Thermo-galvanometer, the, 37
Thomson Mirror Galvanometer, the, 28
Thomson, Prof., S., 159
Torpedo, the, 98
Training station at Porth, 225
Transformer, the, 127
Transmitting instruments, 163
Travers, Prof., 75
Tree stumps, blasting, 19
Tuning-fork a standard of speed, 193
Turret of a battleship, 240
U
Ultra-microscope, the, 209
Ultra-violet rays, 172
V
Varley and the Atlantic cable, 28
Vaseline, 46
Veins or lodes, 113
Vickers, 202
Voltmeter, the, 26
Volts, 22, 24
W
Water a source of heat, 124
Water, soft and hard, 232
Watt, the, 24
Waves caused by ships, recording, 200
Wax models of ships, 199
Welding by electricity, 125
Wells, blasting, 20
Welsbach mantle, the, 124
Whitehead, 99
Wire guns, 238
Wireless telegraphy, 161, 173
Wireless torpedo, the, 102
Wood-meal in explosives, 12
Wood spirit, 49
"Working fluid," the, 68
Y
Yeast, 51
Z
Zero, 68
Zinc in gold recovery, 119
* * * * *
THE RIVERSIDE PRESS LIMITED, EDINBURGH
1917