and engines. He made a special machine for testing fabrics, to decide
which would be most suitable for stretching over strong frames to form
the planes. The fabric must be light, very strong, and offer small
frictional resistance to the air. The testing-machine was fitted with
a nozzle, through which air was forced at a known pace on to the
substance under trial, which met the air current at a certain angle
and by means of indicators showed the strength of its “lift” or
tendency to rise, and that of its “drift” or tendency to move
horizontally in the direction of the air-current. A piece of tin,
mounted at an angle of one in ten to the air-current, showed a “lift”
of ten times its “drift.” This proportion was made the standard.
Experiments conducted on velvet, plush, silk, cotton and woollen goods
proved that the drift of crape was several times that of its lift, but
that fine linen had a lift equal to nine times its drift; while a
sample of Spencer’s balloon fabric was as good as tin.
Accordingly he selected this balloon fabric to stretch over light but
strong frames. The stretching of the material was no easy matter, as
uneven tension distorted it; but eventually the aeroplanes were
completed, tight as drumheads.
The large or central plane was 50 feet wide and 40 long; on either
side were auxiliary planes, five pairs; giving a total area of 5400
square feet.
The steam-engine built to give the motive power was perhaps the most
interesting feature of the whole construction. Maxim employed steam in
preference to any other power as being one with which he was most
familiar, and yielding most force in proportion to the weight of the
apparatus. He designed and constructed a pair of high-pressure
compound engines, the high-pressure cylinders 5 inches in diameter,
the low-pressure 8 inches, and both 1 foot stroke. Steam was supplied
to the high-pressure cylinders at 320 lbs. per square inch from a
tubular boiler heated by a gasolene burner so powerful in its action
as to raise the pressure from 100 to 200 lbs. in a minute. The total
weight of the boiler, burner, and engines developing 350 horse-power
was 2000 lbs., or about 6 lbs. per horse-power.
The two screw-propellers driven by the engine measured 17 feet 11
inches in diameter.
The completed flying-machine, weighing 7500 lbs., was mounted on a
railway-truck of 9-foot gauge, in Baldwyn’s Park, Kent, not far from
the gun-factories for which Sir Hiram is famous. Outside and parallel
to the 9-foot track was a second track, 35 feet across, with a
reversed rail, so that as soon as the machine should rise from the
inner track long spars furnished with flanged wheels at their
extremities should press against the under side of the outer track and
prevent the machine from rising too far. Dynamometers, or instruments
for measuring strains, were fitted to decide the driving and lifting
power of the screws. Experiments proved that with the engines working
at full power the screw-thrust against the air was 2200 lbs., and the
lifting force of the aeroplanes 10,000 lbs., or 1500 in excess of the
machine’s weight.
Everything being ready the machine was fastened to a dynamometer and
steam run up until it strained at its tether with maximum power; when
the moorings were suddenly released and it bounded forward at a
terrific pace, so suddenly that some of the crew were flung violently
down on to the platform. When a speed of 42 miles was reached the
inner wheels left their track, and the outer wheels came into play.
Unfortunately, the long 35-foot axletrees were too weak to bear the
strain, and one of them broke. The upper track gave way, and for the
first time in the history of the world a flying-machine actually left
the ground fully equipped with engines, boiler, fuel, and a crew. The
journey, however, was a short one, for part of the broken track fouled
the screws, snapped a propeller blade and necessitated the shutting
off of the steam, which done, the machine settled to earth, the wheels
sinking into the sward and showing by the absence of any marks that it
had come directly downwards and not run along the surface.
The inventor was prevented by other business, and by the want of a
sufficiently large open space, from continuing his experiments, which
had demonstrated that a large machine heavier than air could be made
to lift itself and move at high speed. Misfortune alone prevented its
true capacities being shown.
Another experimenter on similar lines, but on a less heroic scale than
Sir Hiram Maxim, is Professor S. P. Langley, the secretary of the
Smithsonian Institution, Washington. For sixteen years he has devoted
himself to a persevering course of study of the flying-machine, and
after oft-repeated failures has scored a decided success in his
Aerodrome, which, though only a model, has made considerable flights.
His researches have proved beyond doubt that the amount of energy
required for flight is but one-fiftieth of what was formerly regarded
as a minimum. A French mathematician had proved by figures that a
swallow must develop the power of a horse to maintain its rapid
flight! Professor Langley’s aerodrome has told a very different tale,
affording another instance of the truth of the saying that an ounce of
practice is worth a pound of theory.
A bird is nearly one thousand times heavier than the air it displaces.
As a motor it develops huge power for its weight, and consumes a very
large amount of fuel in doing so. An observant naturalist has
calculated that the homely robin devours per diem, in proportion to
its size, what would be to a man a sausage two hundred feet long and
three inches thick! Any one who has watched birds pulling worms out of
the garden lawn and swallowing them wholesale can readily credit this.
Professor Langley therefore concentrated himself on the production of
an extremely light and at the same time powerful machine. Like Maxim,
he turned to steam for motive-power, and by rigid economy of weight
constructed an engine with boilers weighing 5 lbs., cylinders of 26
ozs., and an energy of 1 to 1-1/2 horse-power! Surely a masterpiece of
mechanical workmanship! This he enclosed in a boat-shaped cover which
hung from two pairs of aeroplanes 12-1/2 feet from tip to tip. The
whole apparatus weighed nearly 30 lbs., of which one quarter
represented the machinery. Experiments with smaller aerodromes warned
the Professor that rigidity and balance were the two most difficult
things to attain; also that the starting of the machine on its aerial
course was far from an easy matter.
A soaring bird does not rise straight from the ground, but opens its
wings and runs along the ground until the pressure of the air raises
it sufficiently to give a full stroke of its pinions. Also it rises
_against_ the wind to get the full benefit of its lifting force.
Professor Langley hired a houseboat on the Potomac River, and on the
top of it built an apparatus from which the aerodrome could be
launched into space at high velocity.
On May 6, 1896, after a long wait for propitious weather, the
aerodrome was despatched on a trial trip. It rose in the face of the
wind and travelled for over half a mile at the rate of twenty-five
miles an hour. The water and fuel being then exhausted it settled
lightly on the water and was again launched. Its flight on both
occasions was steady, and limited only by the rapid consumption of its
power-producing elements. The Professor believes that larger machines
would remain in the air for a long period and travel at speeds
hitherto unknown to us.
In both the machines that we have considered the propulsive power was
a screw. No counterpart of it is seen in Nature. This is not a valid
argument against its employment, since no animal is furnished with
driving-wheels, nor does any fish carry a revolving propeller in its
tail. But some inventors are strongly in favour of copying Nature as
regards the employment of wings. Mr. Sydney H. Hollands, an
enthusiastic aeromobilist, has devised an ingenious cylinder-motor so
arranged as to flap a pair of long wings, giving them a much stronger
impulse on the down than on the up stroke. The pectoral muscles of a
bird are reproduced by two strong springs which are extended by the
upward motion of the wings and store up energy for the down-stroke.
Close attention is also being paid to the actual shape of a bird’s
wing, which is not flat but hollow on its under side, and at the front
has a slightly downward dip. “Aerocurves” are therefore likely to
supersede the “aeroplane,” for Nature would not have built bird’s
wings as they are without an object. The theory of the aerocurve’s
action is this: that the front of the wing, on striking the air, gives
it a downwards motion, and if the wing were quite flat its rear
portion would strike air already in motion, and therefore less
buoyant. The curvature of a floating bird’s wings, which becomes more
and more pronounced towards the rear, counteracts this yielding of the
air by pressing harder upon it as it passes towards their hinder edge.
[Illustration: _M. Santos Dumont’s Airship returning to Longchamps
after doubling the Eiffel Tower, October 19, 1901._]
The aerocurve has been used by a very interesting group of
experimenters, those who, putting motors entirely aside, have floated
on wings, and learnt some of the secrets of balancing in the air. For
a man to propel himself by flapping wings moved by legs or arms is
impossible. Sir Hiram Maxim, in addressing the Aeronautical Society,
once said that for a man to successfully imitate a bird his lungs must
weigh 40 lbs., to consume sufficient oxygen, his breast muscles 75
lbs., and his breast bone be extended in front 21 inches. And unless
his total weight were increased his legs must dwindle to the size of
broomsticks, his head to that of an apple! So that for the present we
shall be content to remain as we are!
Dr. Lilienthal, a German, was the first to try scientific
wing-sailing. He became a regular air gymnast, running down the sides
of an artificial mound until the wings lifted him up and enabled him
to float a considerable distance before reaching earth again. His
wings had an area of 160 square feet, or about a foot to every pound
weight. He was killed by the wings collapsing in mid-air. A similar
fate also overtook Mr. Percy Pilcher, who abandoned the initial run
down a sloping surface in favour of being towed on a rope attached to
a fast-moving vehicle. At present Mr. Octave Chanute, of Chicago, is
the most distinguished member of the “gliding” school. He employs,
instead of wings, a species of kite made up of a number of small
aerocurves placed one on the top of another a small distance apart.
These box kites are said to give a great lifting force for their
weight.
These and many other experimenters have had the same object in
view--to learn the laws of equilibrium in the air. Until these are
fully understood the construction of large flying-machines must be
regarded as somewhat premature. Man must walk before he can run, and
balance himself before he can fly.
There is no falling off in the number of aërial machines and schemes
brought from time to time into public notice. We may assure ourselves
that if patient work and experiment can do it the problem of “how to
fly” is not very far from solution at the present moment.
As a sign of the times, the War Office, not usually very ready to
take up a new idea, has interested itself in the airship, and
commissioned Dr. F. A. Barton to construct a dirigible balloon which
combines the two systems of aerostation. Propulsion is effected by six
sets of triple propellers, three on each side. Ascent is brought about
partly by a balloon 180 feet long, containing 156,000 cubic feet of
hydrogen, partly by nine aeroplanes having a total superficial area of
nearly 2000 square feet. The utilisation of these aeroplanes obviates
the necessity to throw out ballast to rise, or to let out gas for a
descent. The airship, being just heavier than air, is raised by the
135 horse-power motors pressing the aeroplanes against the air at the
proper angle. In descent they act as parachutes.
The most original feature of this war balloon is the automatic
water-balance. At each end of the “deck” is a tank holding forty
gallons of water. Two pumps circulate water through these tanks, the
amount sent into a tank being regulated by a heavy pendulum which
turns on the cock leading to the end which may be highest in
proportion as it turns off that leading to the lower end. The idea is
very ingenious, and should work successfully when the time of trial
comes.
Valuable money prizes will be competed for by aeronauts at the coming
World’s Fair at St. Louis in 1903. Sir Hiram Maxim has expressed an
intention of spending £20,000 in further experiments and prizes. In
this country, too, certain journals have offered large rewards to any
aeronaut who shall make prescribed journeys in a given time. It has
also been suggested that aeronautical research should be endowed by
the state, since England has nothing to fear more than the flying
machine and the submarine boat, each of which tends to rob her of the
advantages of being an island by exposing her to unexpected and unseen
attacks.
Tennyson, in a fine passage in “Locksley Hall,” turns a poetical eye
towards the future. This is what he sees--
“For I dipt into the future, far as human eye could see,
Saw the vision of the world and all the wonder that would be,
Saw the heavens fill with commerce, argosies of magic sail,
Pilots of the purple twilight dropping down with costly bales,
Heard the heavens fill with shouting, then there rained a ghostly dew,
From the nations’ airy navies, grappling in the central blue.”
Expressed in more prosaic language, the flying-machine will primarily
be used for military purposes. A country cannot spread a metal
umbrella over itself to protect its towns from explosives dropped from
the clouds.
Mail services will be revolutionised. The pleasure aerodrome will take
the place of the yacht and motor-car, affording grand opportunities
for the mountaineer and explorer (if the latter could find anything
new to explore). Then there will also be a direct route to the North
Pole over the top of those terrible icefields that have cost
civilisation so many gallant lives. And possibly the ease of transit
will bring the nations closer together, and produce good-fellowship
and concord among them. It is pleasanter to regard the flying-machine
of the future as a bringer of peace than as a novel means of spreading
death and destruction.
TYPE-SETTING BY MACHINERY.
To the Assyrian brickmakers who, thousands of years ago, used blocks
wherewith to impress on their unbaked bricks hieroglyphics and
symbolical characters, must be attributed the first hesitating step
towards that most marvellous and revolutionary of human
discoveries--the art of printing. Not, however, till the early part of
the fifteenth century did Gutenberg and Coster conceive the brilliant
but simple idea of printing from separate types, which could be set in
different orders and combinations to represent different ideas. For
Englishmen, 1474 deserves to rank with 1815, as in that year a very
Waterloo was won on English soil against the forces of ignorance and
oppression, though the effects of the victory were not at once
evident. Considering the stir made at the time by the appearance of
Caxton’s first book at Westminster, it seems strange that an invention
of such importance as the printing-press should have been frowned upon
by those in power, and so discouraged that for nearly two centuries
printing remained an ill-used and unprogressive art, a giant half
strangled in his cradle. Yet as soon as prejudice gave it an open
field, improved methods followed close on one another’s heels. To-day
we have in the place of Caxton’s rude hand-made press great cylinder
machines capable of absorbing paper by the mile, and grinding out
20,000 impressions an hour as easily as a child can unwind a reel of
cotton.
Side by side with the problem how to produce the greatest possible
number of copies in a given time from one machine, has arisen
another:--how to set up type with a proportionate rapidity. A press
without type is as useless as a chaff-cutter without hay or straw. The
type once assembled, as many casts or stereotypes can be made from it
as there are machines to be worked. But to arrange a large body of
type in a short time brings the printer face to face with the
need of employing the expensive services of a small army of
compositors--unless he can attain his end by some equally efficient
and less costly means. For the last century a struggle has been in
progress between the machine compositor and the human compositor,
mechanical ingenuity against eye and brains. In the last five years
the battle has turned most decidedly in favour of the machine. To-day
there are in existence two wonderful contrivances which enable a man
to set up type six times as fast as he could by hand from a box of
type, with an ease that reminds one of the mythical machine for the
conversion of live pigs into strings of sausages by an uninterrupted
series of movements.
These machines are called respectively the Linotype and Monotype.
Roughly described, they are to the compositor what a typewriter is to
a clerk--forming words in obedience to the depression of keys on a
keyboard. But whereas the typewriter merely imprints a single
character on paper, the linotype and monotype cast, deliver, and set
up type from which an indefinite number of impressions can be taken.
They meet the compositor more than half-way, and simplify his labour
while hugely increasing his productiveness.
As far back as 1842 periodicals were mechanically composed by a
machine which is now practically forgotten. Since that time hundreds
of other inventions have been patented, and some scores of different
machines tried, though with small success in most cases; as it was
found that quality of composition was sacrificed to quantity, and that
what at first appeared a short cut to the printing-press was after all
the longest way round, when corrections had all been attended to. A
really economical type-setter must be accurate as well as prolific.
Slipshod work will not pay in the long run.
Such a machine was perfected a few years ago by Ottmar Mergenthaler of
Baltimore, who devised the plan of casting a whole _line of type_. The
Linotype Composing Machine, to give it its full title, produces type
all ready for the presses in “slugs” or lines--hence the name, Lin’ o’
type. It deserves at least a short description.
The Linotype occupies about six square feet of floor space, weighs one
ton, and is entirely operated by one man. Its most prominent features
are a sloping magazine at the top to hold the brass matrices, or
dies from which the type is cast, a keyboard controlling the machinery
to drop and collect the dies, and a long lever which restores the dies
to the magazine when done with.
[Illustration: _By kind permission of The Linotype Co._
_The Linotype Machine. By pressing keys on the key-board the operator
causes lines of type to be set up, cast, and arranged on the “galley”
ready for the printers._]
The operator sits facing the keyboard, in which are ninety keys,
variously coloured to distinguish the different kinds of letters. His
hands twinkle over the keys, and the brass dies fly into place. When a
key is depressed a die shoots from the magazine on to a travelling
belt and is whirled off to the assembling-box. Each die is a flat,
oblong brass plate, of a thickness varying with the letter, having a
large V-shaped notch in the top, and the letter cut half-way down on
one of the longer sides. A corresponding letter is stamped on the side
nearest to the operator so that he may see what he is doing and make
needful corrections.
As soon as a word is complete, he touches the “spacing” lever at the
side of the keyboard. The action causes a “space” to be placed against
the last die to separate it from the following word. The operations
are repeated until the tinkle of a bell warns him that, though there
may be room for one or two more letters, the line will not admit
another whole syllable. The line must therefore be “justified,” that
is, the spaces between the words increased till the vacant room is
filled in. In hand composition this takes a considerable time, and is
irksome; but at the linotype the operator merely twists a handle and
the wedge-shaped “spaces,” placed thin end upwards, are driven up
simultaneously, giving the lateral expansion required to make the line
of the right measure.
A word about the “spaces,” or space-bands. Were each a single wedge
the pressure would be on the bottom only of the dies, and their tops,
being able to move slightly, would admit lead between them. To obviate
this a small second wedge, thin end _downwards_, is arranged to slide
on the larger wedge, so that in all positions parallelism is secured.
This smaller wedge is of the same shape as the dies and remains
stationary in line with them, the larger one only moving.
The line of dies being now complete, it is automatically borne off and
pressed into contact with the casting wheel. This wheel, revolving on
its centre, has a slit in it corresponding in length and width to the
size of line required. At first the slit is horizontal, and the dies
fit against it so that the row of sunk letters on the faces are in the
exact position to receive the molten lead, which is squirted through
the slit from behind by an automatic pump, supplied from a metal-pot.
The pot is kept at a proper heat of 550° Fahrenheit by the flames of a
Bunsen burner.
The lead solidifies in an instant, and the “slug” of type is ready for
removal, after its back has been carefully trimmed by a knife. The
wheel revolves for a quarter-turn, bringing the slit into a vertical
position; a punch drives out the “slug,” which is slid into the galley
to join its predecessors. The wheel then resumes its former horizontal
position in readiness for another cast.
The assembled dies have for the time done their work and must be
returned to the magazine. The mechanism used to effect this is
peculiarly ingenious.
An arm carrying a ribbed bar descends. The dies are pushed up, leaving
the “spaces” behind to be restored to their proper compartment, till
on a level with the ribbed bar, on to which they are slid by a lateral
movement, the notches of the V-shaped opening in the top side of each
die engaging with the ribs on the bar. The bar then ascends till it is
in line with a longer bar of like section passing over the open top of
the entire magazine. A set of horizontal screw-bars, rotating at high
speed, transfer the dies from the short to the long bar, along which
they move till, as a die comes above its proper division of the
magazine, the arrangement of the teeth allows it to drop. While all
this has been going on, the operator has composed another line of
moulds, which will in turn be transferred to the casting wheel, and
then back to the magazine. So that the three operations of composing,
casting, and sorting moulds are in progress simultaneously in
different parts of the machine; with the result that as many as 20,000
letters can be formed by an expert in the space of an hour, against
the 1500 letters of a skilled hand compositor.
How about corrections? Even a comma too few or too many needs the
whole line cast over again. It is a convincing proof of the difference
in speed between the two methods that a column of type can be
corrected much faster by the machine, handicapped as it is by its
solid “slugs,” than by hand. No wonder then that more than 1000
linotypes are to be found in the printing offices of Great Britain.
The Monotype, like the Linotype, aims at speed in composition, but in
its mechanism it differs essentially from the linotype. In the first
place, the apparatus is constructed in two quite separate parts. There
is a keyboard, which may be on the third floor of the printing
offices, and the casting machine, which ceaselessly casts and sets
type in the basement. Yet they are but one whole. The connecting link
is the long strip of paper punched by the keyboard mechanism, and then
transferred to the casting machine to bring about the formation of
type. The keyboard is the servant of man; the casting machine is the
slave of the keyboard.
Secondly, the Monotype casts type, not in blocks or a whole line, but
in separate letters. It is thus a complete type-foundry. Order it to
cast G’s and it will turn them out by the thousand till another letter
is required.
Thirdly, by means of the punched paper roll, the same type can be set
up time after time without a second recourse to the keyboard, just as
a tune is ground repeatedly out of a barrel organ.