providing as many characters; also thirty keys to regulate the spacing
of the words. At the back of the machine a roll of paper runs over
rollers and above a row of thirty little punches worked by the keys.
A key being depressed, an opened valve admits air into two cylinders,
each driving a punch. The punches fly up and cut two neat little holes
in the paper. The roll then moves forward for the next letter. At the
end of the word a special lever is used to register a space, and so on
to the end of the line. The operator then consults an automatic
indicator which tells him exactly how much space is left, and how much
too long or too short the line would be if the spaces were of the
normal size. Supposing, for instance, that there are ten spaces, and
that there is one-tenth of an inch to spare. It is obvious that by
extending each space one-hundredth of an inch the vacant room will be
exactly filled. Similarly, if the ten normal spaces would make the
line one-tenth of an inch too _long_, by _decreasing_ the spaces each
one-hundredth inch the line will also be “justified.”
[Illustration: _By kind permission of_] [_The Monotype Co._
_The Monotype Casting Machine. A punched paper roll fed through the
top of the machine automatically casts and sets up type in separate
letters._]
But the operator need not trouble his head about calculations of this
kind. His indicator, a vertical cylinder covered with tiny squares, in
each of which are printed two figures, tell him exactly what he has to
do. On pressing a certain key the cylinder revolves and comes to rest
with the tip of a pointer over a square. The operator at once presses
down the keys bearing the numbers printed on that square, confident
that the line will be of the proper length.
As soon as the roll is finished, it is detached from the keyboard and
introduced to the casting machine. Hitherto passive, it now becomes
active. Having been placed in position on the rollers it is slowly
unwound by the machinery. The paper passes over a hollow bar in which
there are as many holes as there were punches in the keyboard, and in
precisely the same position. When a hole in the paper comes over a
hole in the hollow bar air rushes in, and passing through a tube
actuates the type-setting machinery in a certain manner, so as to
bring the desired die into contact with molten lead. The dies are, in
the monotype, all carried in a magazine about three inches square,
which moves backwards or forwards, to right or left, in obedience to
orders from the perforated roll. The dies are arranged in exactly the
same way as the keys on the keyboard. So that, supposing A to have
been stamped on the roll, one of the perforations causes the magazine
to slide one way, while the other shoves it another, until the
combined motions bring the matrix engraved with the A underneath the
small hole through which molten lead is forced. The letter is ejected
and moves sideways through a narrow channel, pushing preceding letters
before it, and the magazine is free for other movements.
At the end of each word a “space” or blank lead is cast, its size
exactly determined by the “justifying” hole belonging to that line.
Word follows word till the line is complete; then a knife-like lever
rises, and the type is propelled into the “galley.” Though a slave the
casting machine will not tolerate injustice. Should the compositor
have made a mistake, so that the line is too long or too short,
automatic machinery at once comes into play, and slips the driving
belt from the fixed to the loose pulley, thus stopping the machine
till some one can attend to it. But if the punching has been correctly
done, the machine will work away unattended till, a whole column of
type having been set up, it comes to a standstill.
The advantages of the Monotype are easily seen. In order to save money
a man need not possess the complete apparatus. If he has the keyboard
only he becomes to a certain extent his own compositor, able to set up
the type, as it were by proxy, at any convenient time. He can give his
undivided attention to the keyboard, stop work whenever he likes
without keeping a casting-machine idle, and as soon as his roll is
complete forward it to a central establishment where type is set.
There a single man can superintend the completion of half-a-dozen
men’s labours at the keyboard. That means a great reduction of
expense.
In due time he receives back his copy in the shape of set-up type, all
ready to be corrected and transferred to the printing machines. The
type done with, he can melt it down without fear of future regret, for
he knows that the paper roll locked up in his cupboard will do its
work a second time as well as it did the first. Should he need the
same matter re-setting, he has only to send the roll through the post
to the central establishment.
Thanks to Mr. Lanston’s invention we may hope for the day when every
parish will be able to do its own printing, or at least set up its own
magazine. The only thing needful will be a monotype keyboard supplied
by an enlightened Parish Council--as soon as the expense appears
justifiable--and kept in the Post Office or Village Institute. The
payment of a small fee will entitle the Squire to punch out his speech
on behalf of the Conservative Candidate, the Schoolmaster to compose
special information for his pupils, the Rector to reduce to print
pamphlets and appeals to charity. And if those of humbler degree think
they can strike eloquence from the keys, they too will of course be
allowed to turn out their ideas literally by the yard.
PHOTOGRAPHY IN COLOURS.
While photography was still in its infancy many people believed that,
a means having been found of impressing the representation of an
object on a sensitised surface, a short time only would have to elapse
before the discovery of some method of registering the colours as well
as the forms of nature.
Photography has during the last forty years passed through some
startling developments, especially as regards speed. Experts, such as
M. Marey, have proved the superiority of the camera over the human eye
in its power to grasp the various phases of animal motion. Even rifle
bullets have been arrested in their lightning flight by the sensitised
plate. But while the camera is a valuable aid to the eye in the matter
of form, the eye still has the advantage so far as colour is
concerned. It is still impossible for a photographer by a simple
process similar to that of making an ordinary black-and-white
negative, to affect a plate in such a manner that from it prints may
be made by a single operation showing objects in their natural
colours. Nor, for the matter of that, does colour photography direct
from nature seem any nearer attainment now than it was in the time of
Daguerre.
There are, however, extant several methods of making colour
photographs in an indirect or roundabout way. These various “dodges”
are, apart from their beautiful results, so extremely ingenious and
interesting that we propose to here examine three of the best known.
The reader must be careful to banish from his mind those _coloured_
photographs so often to be seen in railway carriages and shop windows,
which are purely the result of hand-work and mechanical printing, and
therefore not _colour_ photographs at all.
Before embarking on an explanation of these three methods it will be
necessary to examine briefly the nature of those phenomena on which
all are based--light and colour. The two are really identical, light
is colour and colour is light.
Scientists now agree that the sensation of light arises from the
wave-like movements of that mysterious fluid, the omnipresent ether.
In a beam of white light several rates of wave vibrations exist side
by side. Pass the beam through a prism and the various rapidities are
sorted out into violet, indigo, blue, green, yellow, orange and red,
which are called the pure colours, since if any of them be passed
again through a prism the result is still that colour. Crimson, brown,
&c., the composite colours, would, if subjected to the prism, at once
split up into their component pure colours.
There are several points to be noticed about the relationship of the
seven pure colours. In the first place, though they are all allies in
the task of making white light, there is hostility among them, each
being jealous of the others, and only waiting a chance to show it.
Thus, suppose that we have on a strip of paper squares of the seven
colours, and look at the strip through a piece of red glass we see
only one square--the red--in its natural colour, since that square is
in harmony only with red rays. (Compare the sympathy of a piano with a
note struck on another instrument; if C is struck, say on a violin,
the piano strings producing the corresponding note will sound, but the
other strings will be silent.) The orange square suggests orange, but
the green and blue and violet appear black. Red glass has arrested
their ether vibrations and said “no way here.” Green and violet would
serve just the same trick on red or on each other. It is from this
readiness to absorb or stop dissimilar rays that we have the different
colours in a landscape flooded by a common white sunlight. The trees
and grass absorb all but the green rays, which they reflect. The
dandelions and buttercups capture and hold fast all but the yellow
rays. The poppies in the corn send us back red only, and the
cornflowers only blue; but the daisy is more generous and gives up all
the seven. Colour therefore is not a thing that can be touched, any
more than sound, but merely the capacity to affect the retina of the
eye with a certain number of ether vibrations per second, and it makes
no difference whether light is reflected from a substance or refracted
through a substance; a red brick and a piece of red glass have similar
effects on the eye.
This then is the first thing to be clearly grasped, that whenever a
colour has a chance to make prisoners of other colours it will do so.
The second point is rather more intricate, viz. that this imprisonment
is going on even when friendly concord appears to be the order of the
day. Let us endeavour to present this clearly to the reader. Of the
pure colours, violet, green and red--the extremes and the centre--are
sufficient to produce white, because each contains an element of its
neighbours. Violet has a certain amount of indigo, green some yellow,
red some orange; in fact every colour of the spectrum contains a
greater or less degree of several of the others, but not enough to
destroy its own identity. Now, suppose that we have three lanterns
projecting their rays on to the same portion of a white sheet, and
that in front of the first is placed a violet glass, in front of the
second a green glass, in front of the third a red glass. What is the
result? A white light. Why? Because they meet _on equal terms_, and as
no one of them is in a point of advantage no prisoners can be made and
they must work in harmony. Next, turn down the violet lantern, and
green and red produce a yellow, half-way between them; turn down red
and turn up violet, indigo-blue results. All the way through a
compromise is effected.
But supposing that the red and green glasses are put in front of the
_same_ lantern and the white light sent through them--where has the
yellow gone to? only a brownish-black light reaches the screen. The
same thing happens with red and violet or green and violet.
Prisoners have been taken, because one colour has had to _demand
passage_ from the other. Red says to green, “You want your rays to
pass through me, but they shall not.” Green retorts, “Very well; but I
myself have already cut off all but green rays, and if they don’t pass
you, nothing shall.” And the consequence of the quarrel is practical
darkness.
The same phenomenon may be illustrated with blue and yellow. Lights of
these two colours projected simultaneously on to a sheet yield white;
but white light sent through blue and yellow glass _in succession_
produces a green light. Also, blue paint mixed with yellow gives
green. In neither case is there darkness or entire cutting-off of
colour, as in the case of Red + Violet or Green + Red.
The reason is easy to see.
Blue light is a compromise of violet and green; yellow of green and
red. Hence the two coloured lights falling on the screen make a
combination which can be expressed as an addition sum.
Blue = green + violet.
Yellow = green + red.
--------------------
green + violet + red = white.
But when light is passed _through_ two coloured glasses in succession,
or reflected from two layers of coloured paints, there are prisoners
to be made.
Blue passes green and violet only.
Yellow passes green and red only.
So violet is captured by yellow, and red by blue, green being free to
pass on its way.
There is, then, a great difference between the _mixing_ of colours,
which evokes any tendency to antagonism, and the _adding_ of colours
under such conditions that they meet on equal terms. The first process
happens, as we have seen, when a ray of light is passed through
colours _in succession_; the second, when lights stream simultaneously
on to an object. A white screen, being capable of reflecting any
colour that falls on to it, will with equal readiness show green, red,
violet, or a combination; but a substance that is in white light red,
or green, or violet will capture any other colour. So that if for the
white screen we substituted a red one, violet or green falling
simultaneously, would yield blackness, because red takes _both_
prisoners; if it were violet, green would be captured, and so on.
From this follows another phenomenon: that whereas projection of two
or more lights may yield white, white cannot result from any mixture
of pigments. A person with a whole boxful of paints could not get
white were he to mix them in an infinitude of different ways; but with
the aid of his lanterns and as many differently coloured glasses the
feat is easy enough.
Any two colours which meet on equal terms to make white are called
_complementary_ colours.
Thus yellow (= red + green lights) is complementary of violet.
Thus pink (= red + violet lights) is complementary of green.
Thus blue (= violet + green lights) is complementary of red.
This does not of course apply to mixture of paints, for complementary
colours must act together, not in antagonism.
If the reader has mastered these preliminary considerations he will
have no difficulty in following out the following processes.
(_a_) _The Joly Process_, invented by Professor Joly of Dublin. A
glass plate is ruled across with fine parallel lines--350 to the inch,
we believe. These lines are filled in alternately with violet, green,
and red matter, every third being violet, green or red as the case may
be. The colour-screen is placed in the camera in front of the
sensitised plate. Upon an exposure being made, all light reflected
from a red object (to select a colour) is allowed to pass through the
red lines, but blocked by all the green and violet lines. So that on
development that part of the negative corresponding to the position of
the red object will be covered with dark lines separated by
transparent belts of twice the breadth. From the negative a positive
is printed, which of course shows transparent lines separated by
opaque belts of twice their breadth. Now, suppose that we take the
colour-screen and place it again in front of the plate in the position
it occupied when the negative was taken, the red lines being opposite
the transparent parts of the positive will be visible, but the green
and violet being blocked by the black deposit behind them will not be
noticeable. So that the object is represented by a number of red
lines, which at a small distance appear to blend into a continuous
whole.
The violet and green affect the plate in a corresponding manner; and
composite colours will affect two sets of lines in varying degrees,
the lights from the two sets blending in the eye. Thus yellow will
obtain passage from both green and red, and when the screen is held up
against the positive, the light streaming through the green and red
lines will blend into yellow in the same manner as they would make
yellow if projected by lanterns on to a screen. The same applies to
all the colours.
The advantage of the Joly process is that in it only one negative has
to be made.
(_b_) _The Ives Process._--Mr. Frederic Eugene Ives, of Philadelphia,
arrives at the same result as Professor Joly, but by an entirely
different means. He takes three negatives of the same object, one
through a violet-blue, another through a green, and a third through a
red screen placed in front of the lens. The red negative is affected
by red rays only; the green by green rays only, and the violet-blue by
violet-blue rays only, in the proper gradations. That is to say, each
negative will have opaque patches wherever the rays of a certain kind
strike it; and the positive printed off will be by consequence
transparent at the same places. By holding the positive made from the
red-screen negative against a piece of red glass, we should see light
only in those parts of the positive which were transparent. Similarly
with the green and violet positives if viewed through glasses of
proper colour. The most ingenious part of Mr. Ives’ method is the
apparatus for presenting all three positives (lighted through their
coloured glasses) to the eye simultaneously. When properly adjusted,
so that their various parts exactly coincide, the eye blends the three
together, seeing green, red, or violet separately, or blended in
correct proportions. The Kromoscope, as the viewing apparatus is
termed, contains three mirrors, projecting the reflections from the
positives in a single line. As the three slides are taken
stereoscopically the result gives the impression of solidity as well
as of colour, and is most realistic.
(_c_) _The Sanger Shepherd Process._--This is employed mostly for
lantern transparencies. As in the Ives process, three negatives and
three transparent positives are made. But instead of coloured glasses
being used to give effect to the positives the positives themselves
are dyed, and placed one on the top of another in close contact, so
that the light from the lantern passes through them in succession. We
have therefore now quitted the realms of harmony for that of discord,
in which prisoners are made; and Mr. Shepherd has had to so arrange
matters that in every case the capture of prisoners does not interfere
with the final result, but conduces to it.
In the first place, three negatives are secured through violet, green,
and red screens. Positives are printed by the carbon process on thin
celluloid films. The carbon film contains gelatine and bichromate of
potassium. The light acts on the bichromate in such a way as to render
the gelatine insoluble. The result is that, though in the positives
there is at first no colour, patches of gelatine are left which will
absorb dyes of various colours. The dyeing process requires a large
amount of care and patience.
Now, it would be a mistake to suppose that each positive is dyed in
the colour of the screen through which its negative was taken. A
moment’s consideration will show us why.
Let us assume that we are photographing a red object, a flower-pot for
instance. The red negative represents the pot by a dark deposit. The
positive printed off will consequently show clear glass at that spot,
the unaffected gelatine being soluble. So that to dye the plate would
be to make all red _except_ the very part which we require red; and on
holding it up to the light the flower-pot would appear as a white
transparent patch.
How then is the problem to be solved?
Mr. Shepherd’s process is based upon an ordered system of
prisoner-taking. Thus, as red in this particular case is wanted it
will be attained by the _other two_ positives (which are placed in
contact with the red positive, so that all three coincide exactly),
robbing white light of all _but_ its red rays.
Now if the other positives were dyed green and violet, what would
happen? They would not produce red, but by robbing white light between
them of red, green, and violet, would produce blackness, and we should
be as far as ever from our object.
The positives are therefore dyed, not in the same colours as the
screens used when the negatives were made, but in their
_complementary_ colours, _i.e._ as explained above, those colours
which added to the colour of the screen would make white.
The red screen negative is therefore dyed (violet + green) = blue. The
green negative (red + violet) = pink. The violet negative (red +
green) = yellow.
To return to our flower-pot. The red-screen positive (dyed blue) is,
as we saw, quite transparent where the pot should be. But behind the
transparent gap are the pink and yellow positives.
White light (= violet + green + red) passes through pink (= violet +
red), and has to surrender all its green rays. The violet and red pass
on and encounter yellow (= green + red), and violet falls a victim to
green, leaving red unmolested.
If the flower-pot had been white all three positives would have
contained clear patches unaffected by the three dyes, and the white
light would have been unobstructed. The gradations and mixtures of
colours are obtained by two of the screens being influenced by the
colour of the object. Thus, if it were crimson, both violet and
red-screen negatives would be affected by the rays reflected by it,
and the green screen negative not at all. Hence the pink positive
would be pink, the yellow clear, and the blue clear.
White light passing through is robbed by pink of green, leaving red +
violet = crimson.
COLOUR PRINTING.
Printing in ink colours is done in a manner very similar to the Sanger
Shepherd lantern slide process. Three blocks are made, by the help of
photography, through violet, green and red screens, and etched away
with acid, like ordinary half-tone black-and-white blocks. The three
blocks have applied to them ink of a complementary colour to the
screen they represent, just as in the Sanger Shepherd process the
positives were dyed. The three inks are laid over one another on the
paper by the blocks, the relieved parts of which (corresponding to the
undissolved gelatine of the Shepherd positives) only take the ink.
White light being reflected through layers of coloured inks is treated
in just the same way as it would be were it transmitted through
coloured glasses, yielding all the colours in approximately correct
gradations.
LIGHTING.
The production of fire by artificial means has been reasonably
regarded as the greatest invention in the history of the human race.
Prior to the day when a man was first able to call heat from the
substances about him the condition of our ancestors must have been
wretched indeed. Raw food was their portion; metals mingled with other
matter mocked their efforts to separate them; the cold of winter drove
them to the recesses of gloomy caverns, where night reigned perpetual.
The production of fire also, of course, entailed the creation of
light, which in its developments has been of an importance second only
to the improved methods of heating. So accustomed are we to our
candles, our lamps, our gas-jets, our electric lights, that it is hard
for us to imagine what an immense effect their sudden and complete
removal would have on our existence. At times, when floods,
explosions, or other accidents cause a temporary stoppage of the gas
or current supply, a town may for a time be plunged into darkness; but
this only for a short period, the distress of which can be alleviated
by recourse to paraffin lamps, or the more homely candle.
The earliest method of illumination was the rough-and-ready one of
kindling a pile of brushwood or logs. The light produced was very
uncertain and feeble, but possibly sufficient for the needs of the
cave-dweller. With the advance of civilisation arose an increasing
necessity for a more steady illuminant, discovered in vegetable oils,
burned in lamps of various designs. Lamps have been found in old
Egyptian and Etruscan tombs constructed thousands of years ago. These
lamps do not differ essentially from those in use to-day, being
reservoirs fitted with a channel to carry a wick.