Photography And Letter-Press Printing
( Originally Published 1898 )
COMMENTING upon a camera devised by Mr. Friese-Greene for the rapid taking of consecutive photographic views, a photographic journal, in February, 1890, remarked that " the chief value of the machine, or of a modification thereof, may hereafter be found to be in the direction not contemplated by the inventors—at least they have said nothing on this point—namely, in the printing of positives for book illustration, for in positive printing through a negative the amount of light can be made vastly to exceed that present in the photographic street views, so that the limit of speed, especially with improved machines as yet unborn, is at present beyond calculation. One can imagine the possibility of a practically endless band of paper being covered with some sensitive preparation as it unrolls, then passing on to the exposure platform, and afterwards into developing and fixing baths. At the present time exposing a negative on a travelling band three thousand times in five minutes would not be bad work."
These lines were no sooner read by the inventor of the camera referred to than he saw the feasibility of the idea which the editor had thrown out, and the thing began to take shape in his mind. A few months later he had constructed a model which fully answered to his expectation, and the invention was patented 1891). About the same time (October 29, 1890 , this model was exhibited in the Literary and Scientific Institution of Bath by the inventor, who also read a paper upon it, which, amongst other things, contained a forecast of the use to which the invention might be turned. Speaking of the effect the original idea had upon his mind, Mr. Greene said : " My blood was fired with enthusiasm, for I thought of taking a scene in Hyde Park or in the City, where the ceaseless stream of life is never ending, by the machine camera one day, and producing in the course of a few hours a paper which could be delivered to the public showing, true to nature, all the movements of life, or anything that might be of interest which was photographed at the time. . . . A well-known person's photograph, with his letter, could be copied by photography and put in print much more quickly than you could set up the type for the letter, leave alone a block—which would take days—for the likeness, and then not be so perfect as it would come out being printed by light alone, for you could not equal the texture and detail by the block process that you could obtain by the other."
When this forecast was made, the invention had not gone beyond the rough model stage. But by that model was produced a long band of photographs printed from half-plates, with gas as the illuminant, the exposure being almost instantaneous. The invention having gone so far, and been protected by patent, the matter was allowed to rest. Many persons saw the model, and one or two were convinced that there was in it the germ of a wonder-working machine—to be produced some day. It was not, however, until some time in 1896 that anything was done towards putting the invention to a thoroughly practical test. When that was done—which was rendered possible through the intervention of a capitalist—it was found to be possible to make great improvements in the machine, and to obtain the end aimed at in various ways; so much so, indeed, that it was deemed advisable to take out fresh patents.
As already said, the first experiments were made with the original model ; but, as this allowed of the printing upon one side of the paper only, and from half-plate negatives, it was, at an early stage of the experiments, decided to construct a machine large enough to print eight pages of the Strand Magazine, namely, four on the one side of the paper and four on the other.
The machine, as will be seen from the illustration (Fig. 34), consists of a box for the printing process, and a number of tanks or troughs to receive the developing, fixing, and finishing solutions. The box consists of two separated chambers for containing the negatives, the first chamber containing the negatives to be printed on the upper side of the paper, and the second chamber containing those to be impressed on the under side of the paper. Each chamber constitutes practically a dark room, with a sliding shutter to admit the light, the light being contained in a separate compartment called the light box, divided from the chamber proper by the shutter. The light is supplied by incandescent electric lamps, and may be diffused or reflected from a mirror.
The negatives are firmly fixed in a frame, and the frames, fitted with grooves, are made to slide in and out for the purpose of changing the negatives, etc. When in position the negatives are in their respective dark chambers, that for printing the upper surface of the paper just above, that for printing the under surface just below, the central line of the machine along which the sensitized paper is carried. Immediately under the paper in the first chamber, and immediately over it in the second, is a platen or pressing-plate, faced with soft felt, which, when exposure is made, presses the paper upon the under side of the negative.
The paper to be printed on is contained upon a roller, and is either already sensitized, or it may be sensitized on its way into the machine by passing through a trough charged with the necessary emulsion. It goes into the machine through a slot, and, as soon as it has filled the two chambers by the action of the machine, the apertures in the light boxes open, while simultaneously the platens press the paper against the negatives, steadying it, and thus the exposure is made.
The instant the exposure is made, the respective apertures close, the pressure of the platens is removed, and the printed portion of the paper is carried forward, giving place to a fresh, unprinted portion. This intermittent motion of the machine proper, which is obtained by means of a pawl, is then repeated, and, with each forward movement of the paper, a portion of the sensitized surface is exposed to the light, first on the upper and then on the under side. As soon as the paper, thus printed upon, emerges from the printing box through a Slot, the intermittent motion is converted into a continuous one, which is maintained uniformly while the paper is being carried successively, by means of glass rollers, through the tanks containing the developing, fixing, and clearing solutions, and so finally into an enclosed chamber or box filled with hot air or exhaust for drying.
From the description it will be understood that every section of the band of paper equivalent in length to an intermittent feed is first printed on the upper face, and then on the lower face; and that, while one section is being printed from the negative in the first chamber, the next following section is being printed from the negative in the second chamber. When it is desired to print on one side of the sensitized paper only, one or other of the chambers is not supplied with a negative, and of course the electric lamps of the respective light box are shut off.
An important consideration connected with the working of the machine is that both the exposure and the development are being carried on at the same time, so that the operator who is controlling the machine is able to see at a glance if the picture or printing is not coming out as it should. If there is over-exposure, he can easily, by an electrical resistance register, adjust the light to the negative. In the same way he can modify or strengthen the developer to the needs of the case.
A smaller machine, for purely photographic purposes, is made single for printing upon one side of the sensitized paper only. These can be adapted for use either with an incandescent lamp or with an ordinary oil lamp. When the latter is employed, there is no difficulty in adjusting the light to the quality of the negative.
The negatives employed may be either negatives produced directly by photography, or they may be photographs of pages of letter-press printing; or a negative may be used in which the two are combined—an ordinary photograph, presenting a view or a person, to which a letter-press description has been added—or other combinations may be made; even an author's own MS. might be printed from.
By a later development of the machine, which need not be explained here, further than to say that the intermittent up-and-down motion is re-placed by a cylindrical arc (similar to that of the rotary printing machine), a much higher rate of speed can be obtained than by the platen press.
In further development of his idea, the inventor has patented a machine whereby he does away with the use of ordinary type, employing in their place a sort of typewriter (worked by keys), which yields its impression by means of photography.
It will be seen that the new photographic printing machine is very simple in construction, and it is believed that by it the cost of printing will be greatly reduced, as well as the quality of it greatly improved, especially as regards the printing of illustrated books, newspapers, &c. There are no complicated movements requiring expensive and heavy machinery; and, indeed, so little friction is there that the machine is almost noiseless. As regards its artistic value, those who have seen prints produced by it affirm that, as regards its variety and delicacy of tones, and the uniform quality of impressions, it outdoes anything that has gone before. Whether it will in the long-run sustain this high praise or not, time will show ; but, in any case, it must be acknowledged to be a striking development of photography—that wonder-worker of the sciences.