side of the sheet, so that when they had been half printed by one
machine, they had then to be passed through the other, in order to be
“perfected,” as it is technically termed. These machines were greatly
improved by Messrs. Applegath and Cowper, who contrived also a
modification by which the sheets could be perfected in one and the same
machine. As the principle of these machines has been followed, with more
or less diversity of detail, in most of the printing machines at present
in use, it is very desirable to lay that principle clearly before the
reader. The diagram, Fig. 151, will make the action of Applegath and
Cowper’s single-printing machine easily understood. The type is set up
on a flat form, A B, which occupies part of the horizontal table, C D,
the rest of which, A C, is the inking table. E is a large cylinder,
covered with woollen cloth, which forms the “blanket.” The paper passes
round this cylinder, and it is pressed against the form. The small black
circles, _f_, _g_, _h_, _k_, _l_, _m_, _n_, represent the rollers for
distributing the ink. _f_ is called the _ductor_ roller. This roller,
which revolves slowly, is made of metal, and parallel to it is a plate
of metal, having a perfectly straight edge, nearly, but not quite,
touching the cylinder, and at the other side, as well as at the
extremities, bent upwards, so as to form a kind of trough, to contain
the ink, as a reservoir. The slow rotation of the ductor conveys the ink
to the next roller, which is covered with composition, and being made to
move backwards and forwards between the ductor roller and the table at
certain intervals, it is termed the _vibrating_ roller. The ink having
thus reached the inking-table, is spread evenly thereon by the
_distributing rollers_, _h_, _k_, and it is taken up from the inking
table, as the latter passes under, by the _inking_ rollers, _l_, _m_,
_n_. The table, C D, as a whole is constantly moving right and left in a
horizontal direction, so that the form passes alternately under the
impression cylinder, E, and the inking rollers, _l_, _m_, _n_. The axles
of the inking and distributing rollers are made long and slender, and
instead of turning in fixed bearings, they rest in slots or notches, in
order that, as the form passes below them, they may be raised, so that
they rest on the inking slab, and on the types, only by their own
weight. They are placed not quite at right angles to the direction of
the table, but a little diagonally. The sliding motion caused by this,
helps very much in the uniform spreading of the ink. By these
arrangements the form is evenly smeared with ink, since each inking
roller passes over it _twice_ before it returns to meet the paper under
E.
[Illustration:
FIG. 152.—_Diagram of Applegath and Cowper’s Perfecting Machine._
]
[Illustration:
FIG. 153.—_Cowper’s Double Cylinder Machine._
]
Fig. 152 is a similar diagram, to show the action of the double or
perfecting printing machine, in which the sheets are printed on both
sides. It will be observed that the general arrangement of impression
cylinder, rollers, &c., is represented in duplicate, but reversed in
direction. There are also two cylinders, B B, the purpose of which, as
may be gathered from an inspection of the diagram, is to reverse the
sheets of paper, so that after one side has been printed under the
cylinder, E´, the blank surface may be turned downward, ready to receive
the impression from the form, A B. Fig. 153 gives a view of the Cowper
and Applegath double machine, as actually constructed. The man standing
up is called the _feeder_ or _layer-on_. He pushes the sheets forward,
one by one, towards the tapes, which carry them down the farther side of
the more distant cylinder, under which they pass, receiving the
impression; and so on in the manner already indicated in the diagram,
Fig. 152, until finally they reach a point where, released by the
separation of the two sets of tapes, they are received by the
_taker-off_ (the boy who is represented seated on the stool), and are
placed by him on a table. The bed or table which carries the form moves
alternately right and left, impelled by a pinion acting in a rack
beneath it, in such a manner that the direction of the table’s motion is
changed at the proper moment, while the driving pulley continues to
revolve always in the same direction. The movements of the table and of
the cylinders are performed in exact harmony with each other, for these
pieces are so connected by trains of wheels and rack-work that the
sheets of paper may always receive the impression in the proper position
as regards the margins, and therefore, when the sheets are printed on
both sides, the impressions will be exactly opposite to each other. This
gives what is technically called “true register,” and as this cannot be
secured unless the paper travels over both cylinders at precisely the
same rate, these are finished with great care by turning their surfaces
in a lathe to exactly the same diameter. The action of the machine will
not be fully understood without a glance at the arrangement of the
endless tapes which carry the paper on its journey. The course of these
may be followed in Fig. 154, and a simple inspection of the diagram will
render a tedious description unnecessary.
[Illustration:
FIG. 154.—_Tapes of Cowper’s Machine._
]
In Fig. 155 we have a representation of a steam-power printing machine,
such as is now very largely used for the ordinary printing of books,
newspapers of moderate circulation, hand-bills, &c., and in all the
ordinary work of the printing press. In this the table on which the form
is placed has a reciprocating motion, but the large cylinder moves
continuously always in the same direction. The feeder, or layer-on,
places the sheet of paper against certain stops, and at the right moment
the sheet is nipped by small steel fingers, and carried forwards to the
cylinder, which brings it into contact with the inked type. This is done
with much accuracy of register, for the impression cylinders gear in
such a manner with the rest of the parts that their revolutions are
synchronous. This is a perfecting machine, for the paper, after having
received the impression on one side, is carried by tapes round the other
cylinder, where it receives the impression on the other side, “set-off
sheets” being passed through the press at the same time. The axles of
the impression cylinders are mounted at the ends of short rocking beams,
by small oscillations of which the cylinders are alternately brought
down upon, or lifted off, the form passing below them. A machine of this
kind can print 900 impressions per hour, even of good bookwork, and for
newspaper or other printing, where less accuracy and finish are
required, it may be driven at such a rate as to produce 1,400 perfected
impressions per hour.
[Illustration:
FIG. 155.—_Messrs. Hopkinson and Cope’s Perfecting Machine._
]
The machines used for lithographic printing by steam power are almost
identical in their general arrangement with that just described, which
may be taken as a representative specimen of the modern printing
machine.
To such machines as those already described the world is indebted for
cheap books, cheap newspapers, and cheap literature in general. But
when, with railways and telegraphs, came the desire for the very latest
intelligence, the necessities of the newspaper press, as regards
rapidity of printing, soon required a greater speed than could possibly
be attained by any of the flat form presses; for in these the table,
with the forms placed upon it, is unavoidably of a considerable weight,
and this heavy mass has to be set in motion, stopped, moved in the
opposite direction, and again stopped during the printing of each sheet.
The shocks and strains which the machine receives in these alternate
reversals of the direction of the movement impose a limit beyond which
the speed cannot be advantageously increased. When Mr. Applegath was
again applied to by the proprietors of the “Times” to produce a machine
capable of working off a still larger number of impressions, he decided
upon abandoning the plan of reciprocating movement, and substituting a
continuous rotary movement of the type form. And he successfully
overcame the difficulties of attaching ordinary type to a cylindrical
surface. The idea of placing the type on a rotating cylinder is due to
Nicholson, who long ago proposed to give the types a wedge shape, so
that the pieces of metal would, like the stones of an arch, exactly fit
round the cylindrical surface. The wedge-shaped types were, however, so
liable to be thrown from their places by the centrifugal force, that
Nicholson proposed also certain mechanical methods of locking the types
together after they had been placed on the circumference of the drum.
The plan he suggested for this purpose involved, however, such an
expenditure of time and trouble that his idea was never carried into
practice. Mr. Applegath used type of the ordinary kind, which was set up
on flat surfaces, forming the sides of a prism corresponding to the
circumference of his revolving type cylinder, which was very large and
placed vertically. The flat surfaces which received the type were the
width of the columns of the newspaper, and the type forms were firmly
locked up by screwing down wedge-shaped rules between the columns at the
angles of the polygon. These form the “column rules,” which make the
upright lines between the columns of the page, and by their shape they
served to securely fix the type in its place. The diameter of the
cylinder to which the form was thus attached was 5 ft. 6 in., but the
type occupied only a portion of its circumference, the remainder serving
as an inking table. Round the great cylinder eight impression rollers
were placed, and to each impression roller was a set of inking rollers.
At each turn, therefore, of the great cylinder eight sheets received the
impression. These cylinders were, as already stated, placed vertically,
and, as it was necessary to supply the sheets from horizontal tables, an
ingenious arrangement of tapes and rollers was contrived, by which each
sheet was first carried down from the table into a vertical position,
with its plane directed towards the impression roller, in which position
it was stopped for an instant, then moved horizontally forwards round
the impression cylinder, and was finally brought out, suspended
vertically, ready for a taker-off to place on his pile. This machine
gave excellent results as to speed and regularity. From 10,000 to 12,000
impressions could be worked off in an hour, and the advantage was
claimed for it of keeping the type much cleaner, by reason of its
vertical position. The power of this machine may be judged of from one
actual instance. It is stated that of copies of the “Times” in which the
death of the Duke of Wellington was announced, 14th November, 1852, no
less than 70,000 were printed in one day, and the machines were not once
stopped, either to wash the rollers or to brush the forms. It may be
mentioned, in order to give a better idea of the magnitude of the
operation of printing this one newspaper, that one average day’s copies
weigh about ten tons, and that the paper for the week’s consumption
fills a train of twenty waggons.
At the “Times” office and elsewhere, the vertical machine has some years
ago been superseded by others with horizontal cylinders. The fastest,
perhaps, of all these printing machines is that which is now known as
the “Walter Press,” so called either because its principle was suggested
by the proprietor of the “Times,” or merely out of compliment to him.
The improvements which are embodied in the Walter Press have been the
subject of several patents taken out in the names of Messrs. MacDonald
and Calverley, and it is to these improvements that we must now direct
the attention of the reader. But we must premise that such machines as
the Walter Press became possible only by the discovery of the means of
rapidly producing what is called a stereotype plate from a form of type.
A full account of the methods of effecting this is reserved for a
subsequent article, but here it may suffice to say, that when a thick
layer of moist cardboard, or rather a number of sheets of thin unsized
paper pasted together and still quite moist, is forced down upon the
form by powerful pressure, a sharp even mould of the type is obtained,
every projection in the latter producing a corresponding depression in
the _papier maché_ mould. When the paper mould is dry, it may be used
for forming a _cast_ by pouring over it some fusible metallic alloy,
having the properties of becoming liquid at a temperature which will not
injure the mould, of taking the impressions sharply, and of being
sufficiently hard to bear printing from. One of the improvements in
connection with the Walter Press is in the mode of forming cylindrical
stereotype casts from the paper mould. For this purpose the mould is
placed on the _internal_ surface of an iron semi-cylinder, with the face
which has received the impression of the type inwards. The central part
of the semi-cylinder is occupied by a cylindrical iron core, which is
adjusted so as to leave a uniform space between its convex surface and
the concave face of the mould. Into this space is poured the melted
metal, and its pressure forces the mould closely against the concave
cylindrical surface to which it is applied, so that the thickness
becomes quite uniform. The iron core has a number of grooves cut round
it, and these produce in the cast so many ribs, or projections, which
encircle the inner surface, and serve both to strengthen the cast and
afford a ready means of obtaining an exact adjustment. Not the complete
cylinder, but only half its circumference, is cast at once, the axis of
the casting apparatus being placed horizontally, and the liquid metal
poured in one unbroken stream between the core and the mould from a
vessel as long as the cylinders. Fig. 156 is a section of the casting
apparatus, in which _a_ is the core, _b_ the _papier maché_ mould, _c_
the iron semi-cylinder containing it, _d_ the metal which has been
poured in at the widened space, _e_. When the metal has solidified, the
core is simply lifted off, and the cast is then taken out, in the form
of a semi-cylinder, the internal surface of which has exactly the
diameter of the external surface of the roller of the machine on which
it is to be placed, in company with another semi-cylindrical plate, so
that the two together encircle half the length of the roller, and when
another pair of semi-cylinders have been fixed on the other part of the
roller, the whole matter of one side of the newspaper sheet, usually
four pages, is ready for printing. One great advantage of working from
stereotype casts made in this way is that the form-bearing cylinder of
the machine has no greater circumference than suffices to afford space
for the matter on one side of the paper. The casts are securely fixed on
the revolving cylinder by elbows, which can be firmly screwed down. The
casts are usually made to contain one page each, so that four
semi-cylinders, each half the length of the revolving cylinder, are
fixed on the circumference of the latter. The process of casting in no
way injures the paper mould, which is in fact generally employed to
produce several plates.
[Illustration:
FIG. 156.
]
[Illustration:
FIG. 157.—_Diagram of the Walter Press._
]
The Walter Machine is not fed with separate sheets of paper, but takes
its supply from a huge roll, and itself cuts the paper into sheets after
it has impressed it on both sides. This is done by a very simple but
effective plan, which consists in passing the paper between two
equal-sized rollers, the circumference of which is precisely the length
of the sheets to be cut. These rollers grip the paper, but only on the
marginal spaces; and on the circumference of one of them, and parallel
to its axis, is a slightly projecting steel blade, which fits into a
corresponding recess, or groove, in the circumference of the other, and
at this time the whole width of the sheet is firmly held by a projecting
piece acted on by a spring. Although the Walter Machine, as actually
constructed, presents to the uninitiated spectator an apparently endless
and intricate series of parallel cylinders and rollers, yet it is in
reality exceedingly simple in principle, as may be seen by the diagram
given in Fig. 157. In this we may first direct the reader’s attention to
the two cylinders, F_{1}, F_{2}, which bear the stereotype casts—one of
the matter belonging to one side of the sheet, the other of the matter
belonging to the other side, for the Walter Press is a perfecting
machine—and the web of paper having been printed by F_{1}, against which
it is pressed by the roller, P_{1}, passes straight, as shown by the
dotted line, to the second pair of cylinders, in order to be printed on
the other side; and here, of course, the form cylinder, F_{2}, is below,
and the impression cylinder, P_{2}, above, and an endless cleaning
blanket is supplied to the latter to receive the _set-off_. The web of
paper then passes between the cutting rollers, C, C_{1}, by which it is
cut in sheets. But the knife has a narrow notch in the centre, and one
at each end, so that the paper is not severed at those parts, narrow
strips or tags being left, which maintain for a while a slight
connection. But the tapes, _t_{1}_, _t_{2}_, between which the paper is
now carried, are driven at a rather quicker rate than the web issues
from C, C_{1}; and the result is, that the tags are torn, and the sheet
becomes separated from the portion next following it. Thus, as a
separate sheet, it arrives at the horizontal tapes, _h_, and is brought
to another set of tapes mounted on the frame, _r_, rocking about the
centre, _c_, by which it is brought finally to the tapes, _f_{1}_,
_f_{2}_, which by the movement of _r_ receive the sheets alternately. A
sheet-flyer, _s_, oscillates between the tapes, _f_{1}_, _f_{2}_; and as
fast as the sheets arrive, lays them down right and left alternately,
and it only remains for the piles, _p_{1}_, _p_{2}_ so formed, to be
removed. The inking apparatus of each form-cylinder is indicated by the
series of rollers marked I_{1}, I_{2}; and in this part of the machine
there are also some improvements over former presses, for the
distributing rollers are not made of composition, but of iron, turned
with great exactness to a true surface, and arranged so as not quite to
touch each other. At D is an apparatus for damping the paper, in which
there are hollow perforated cylinders, covered by blanket, and filled
with some porous material, which is kept constantly wet. These cylinders
being made to rotate rapidly, the centrifugal force causes the water to
find its way uniformly to the outside. Here the paper also passes
between rollers intended to flatten and to stretch it. At R is the great
roll of paper, from which the machine takes its supply. These rolls
contain, perhaps, five miles length of paper, and at first it was a
matter of some difficulty to fix them firmly on their wooden axles, so
that they might be steadily unwound; but the contrivers of the Walter
Press make these spindles as tight as may be required by forming them in
wedge-shaped pieces, which can be made to increase the thickness of the
spindle by drawing one upon another by screws.
The great speed of the Walter Machine is secured by the paper being
drawn by the machine itself from a continuous web, instead of being laid
on in a separate sheet, so that the machine is not dependent on the
dexterity of the layers-on, who are besides necessarily highly-skilled
workmen, and therefore a great economy of wages results from using a
machine which does not require their services; and as the Walter Press
also itself lays down the perfected sheets, the necessary attendants are
as few as possible. The waste of paper and loss of time by stoppages are
said to be extremely small with this machine.
Fig. 148 will give some idea of the appearance of the printing-room
where one of the leading London daily papers is being printed by Walter
Presses.
Another fast printing machine is the type revolving cylinder machine
invented by Colonel Richard M. Hoe, and manufactured by the well-known
firm of Hoe and Company, New York, with whose name the history of fast
printing machines must ever be associated. In these machines the type is
placed on the circumference of a cylinder which rotates about a
horizontal axis, and the difficulties of securely locking up the type
are successfully overcome. The machines are made with two, four, six,
eight, or ten impression cylinders, and at each revolution of the great
cylinder the corresponding number of impressions are produced. The
engraving on the opposite page, Fig. 158, represents the two-cylinder
machine, and an examination of the figure will render its general action
intelligible. The form of type occupies about one-fourth of the
circumference of the great cylinder, the remainder being used as an
ink-distributing surface. Round this main cylinder, and parallel to it,
are placed smaller impression cylinders, from two to ten in number,
according to the size of the machine. When the press is in operation,
the rotation of the main cylinder carries the type form to each
impression cylinder in succession, and it there impresses the paper,
which is made to arrive at the right time to secure true register. One
person is required for each impression cylinder, to supply the sheets of
paper, which have merely to be laid in a certain position, when, at the
proper moment, they are seized by the “grippers,” or fingers of the
machine, and after having been printed, are carried out by tapes, and
laid in heaps by self-acting sheet-flyers, by which the hands which are
required to receive and pile the sheets in other machines are dispensed
with. The ink is contained in a fountain placed beneath the main
cylinder, and is conveyed by means of rollers to the distributing
surface of the main cylinder. This surface, being lower than that of the
type forms, passes by the impression cylinders without touching them.
For each impression cylinder there are two inking rollers, receiving
their supply of ink from the distributing surface of the main cylinder.
These inking rollers, the bearings of which are, by springs, drawn
towards the axis of the main cylinder, rise as the form passes under
them, and having inked it, they again drop on to the distributing
surface. Each page of the matter is locked up on a detachable segment of
the large cylinder, which segment constitutes its bed and chase. The
column-rules are parallel with the shaft of the cylinder, and are
consequently straight, while the head, advertising, and dark rules have
the form of segments of a circle. The column-rules are in the shape of a
wedge, with the thin end directed towards the axis of the cylinder, so
as to bind the types securely. These wedge-shaped column-rules are held
in their place by tongues projecting at intervals along their length,
and sliding in grooves cut crosswise in the face of the bed. The spaces
in the grooves between the column-rules are accurately fitted with
sliding blocks of metal level with the surface of the bed, the ends of
the blocks being cut away underneath, to receive a projection on the
sides of the tongues of the column-rules. The locking up is effected by
means of screws at the foot of each page, by which the type is held as
securely as in the ordinary manner upon a flat bed. The main cylinder of
the machine represented in Fig. 158 has a diameter of 3 ft. 9 in., and
its length is, according to the size of the sheets to be printed, from 4
ft. 5 in. to 7 ft. 4 in. The whole is about 20 ft. long, 10 ft. wide,
including the platforms, and a height of 9 ft. in the room in which it
is placed suffices for its convenient working. The steam power required
is from one to two horse-power, according to the length of the main
cylinder. The speed of these machines is limited only by the ability of
the feeders to supply the sheets fast enough. The ten-cylinder machine
has, of course, ten impression cylinders, instead of two, and there are
ten feeding-tables, arranged one above the other, five on each side. The
main cylinder has a diameter of 4 ft. 9 in., and is 6 ft. 8 in. long.
The machine occupies altogether a space of 31 ft. by 16 ft., and its
height is 18 ft. A steam engine of eight horse-power is sufficient to
drive the ten-cylinder machine, which is then capable of producing
25,000 impressions per hour. The mechanism of the larger machines is
precisely similar to that of the two-cylinder machine, except such
additional devices as are necessary to carry the paper to and from the
main cylinder at four, six, eight, or ten points of its circumference.
Much admirable contrivance is displayed in the manner of disposing
feeders as closely as possible round the central cylinder.
[Illustration:
FIG. 158.—_Messrs. Hoe’s Type Revolving Cylinder Machine._
]
In some machines, such as Messrs. Hoe’s, Fig. 158, the sheet-flyers are
interesting features, for they form an efficient contrivance for laying
down and piling up, with the greatest regularity, sheet after sheet as
it issues from the press. The sheet-flyer is in fact an automatic
taker-off, and therefore it supersedes the services of the boy who would
otherwise be required. It is simply a light wooden framework of parallel
bars, turning on one of its sides as a centre; and the tapes carrying
the sheet, passing down between the bars, bring the paper down upon the
frame, where its progress is then stopped, the frame makes a rapid turn
on its centre, lays down the sheet, and quickly rises to receive another
from the tapes. One can hardly see a printing machine in action without
being struck with the deftness with which the sheet-flyer does its duty;
for the precision with which it receives a sheet, lays it down, and then
quickly returns, to be ready for the next, suggest to the mind of the
spectator rather the movements of a conscious agent than the motions of
an unintelligent piece of mechanism. The sheet-flyer is seen at the
left-hand side of Fig. 158, where it is in the act of laying down a
sheet on the pile it has already formed.
[Illustration:
FIG. 159.—_Messrs. Hoe’s “Railway” Machine._
]
[Illustration:
FIG. 160.—_Napier’s Platen Machine._
]