Discoveries and Inventions of the Nineteenth Century

matrix of each letter (or sign), and special to it. The meaning of this will be seen presently. The diagram Fig. 313c will help us to see how these matrices are assembled by touches of the finger on the required letters as marked on the keyboard at D. The matrices are assorted and stored in separate channels in the “matrix” magazine, A, a portion of its cover being here represented as broken off in order to show the channels. It will readily be understood 647that, by a system of levers connected with each key, the corresponding matrix is released by means of an escapement (B´), and falls down one of the channels E on to the travelling belt F, which conveys it to composing 648stick G, in which the matrices successively assemble in the order to constitute a line (Fig. 313c), in which observe that the several words are separated by spaces formed by long wedges of steel, the thick ends of which hang down considerably below the line of matrices. These are dropped one by one from a store at I (Fig. 313c), when required, by a touch on the key-bar J; two of them are shown in position in the assembling stick G. In Fig. 313a a bell is seen in front of the keyboard, and this is automatically rung by a mechanical device when the line of matrices is approaching in length to that allotted to the work. At this point the operator has to consider whether he can complete the line with another, or with how many syllables of a word, and he touches the keys of the required letters. The assembling stick then contains all the matrices comparatively loosely packed side by side, for the words are as yet separated by only the thin edges of the space wedges. A touch of the operator on a lever brings into play another part of the mechanism by which the composed line is bodily lifted a short way, then moved horizontally, and conveyed to the “mould wheel,” in which there is a slot, adjustable in length and width, and the line is here firmly pressed against the face of the wheel in such a way that the slot coincides with the line of hollow letters on the edges of the matrices, as shown in Fig. 313b. This moulding 649arrangement is not the least ingenious device in this machine, and well deserves attention. Before the moulding takes place, but while the line is in its place, the wedge spaces are pushed up through the matrices by another portion of the mechanism, and thus the line is immediately “justified,” as the printers term it; that is, the wedges rise up, separating the words, more or less, until the line has exactly its assigned length, and the words are, at the same time, separated by equal spaces. A melting-pot behind the mould-wheel contains a quantity of fusible metal, resembling stereotype metal, which is maintained at just the temperature of fluidity by a regulated gas burner. At the right moment a plunger is forced into the fluid mass, causing it to rise through a kind of spout to the level of the slot in the wheel, and be forced through that into the line of letters. The metal instantly solidifies in the mould, the line of matrices is removed on a bar to a new position at R, Fig. 313c, and the wheel then makes a quarter of a turn, bringing the mould from the horizontal into a vertical position (Fig. 313e). The linotype is subjected to the operation of certain knives (not shown), by which it is pared smoothly to the exact thickness and height required, and finally ejected, as shown in Fig. 313e, dropping in its proper order into a receiving galley. The line, as completed, has the shape represented in Fig. 313g, and a number of these lines assembled constitute a “form,” answering all the purposes of the ordinary forms consisting of separate type. These last, after having served their purpose, must be “distributed,” that is, each single letter must be returned to the case from which it was taken by the compositor; but the linotype form, after use, is simply returned to the melting-pot for its metal to be recast into new forms. The forms can, of course, remain standing for any length of time at the mere expense of keeping the metal unemployed. One advantage 650of the linotype is that the printing is all done from new clean-faced forms, instead of the old and dull-faced characters of ordinary type that have been much used, but have to be resorted to under ordinary circumstances. Fig. 313e.—A Finished Line entering Galley. Fig. 313f.—The Melting Pot and Mould Wheel. It may occur to the reader that errors in linotype would be much more difficult of correction than those occurring with the ordinary type composed by hand. If by chance a wrong matrix appears in the line, this can be changed by hand at once; but supposing that the operator overlooks some error in reading the assembled line, which, observe, he reads with the characters arranged as they will appear in the impression, or that he has misread his manuscript, and the line is cast, assembled into a “form” with the rest, and then in the printed proof the error is discovered, how is it to be rectified? Simply by removing the faulty linotype from the form, and casting a new one. This is so quickly and easily done that it has been found by actual test between linotype and ordinary type matter containing the same defects, that the former could be corrected in less than one-third of the time required for the latter. We left the line of matrices at R (Fig. 313c), and we must now indicate the method by which each is automatically returned to its own magazine, an operation for which much ingenious mechanism has been contrived, of which the details cannot be well described in this place. The line 651having reached R, the space wedges are disengaged from it and removed to their receptacle at I, while the matrices become engaged by their teeth in the grooves of a horizontal bar, and then the bar is grasped by a lever which lifts it up to the distributing arrangement at the top of the machine, where the teeth of the matrices come to the exact level of the grooves of the distributor bar T. The line is then pushed laterally, the sides of the matrices become engaged in the hollows of two parallel screws U, by which, while suspended only by such of their inclined teeth as the corresponding groove of the distributor can support, they are made to slowly travel along from left to right until each reaches a certain point, namely, that at which its sustaining V grooves on the bar are interrupted by cuts which permit it to drop into its own special magazine. A little consideration will show how, by various combinations of the notches on the matrix, and corresponding cuts at the right places in the grooves of the bar, each matrix may be made to move along until it reaches a determinate place, and there dropped. Compare Fig. 313b and Fig. 313i. Each matrix thus again deposited in its proper magazine has completed the circuit of the machine, or, at least, has passed from the bottom of its magazine to the assembling stick, hence to the mould, and, by the distributor, finds its way back to the top of its magazine, whence, in its turn, it will descend to perform again the same duty. Fig. 313g.—The Finished Line. Fig. 313h.—Lines assembled into a “Form.” It must be understood that, beyond the operator’s touches on the key-board, 652and that required to send off the assembled line to the moulding apparatus, all the actions are done automatically without the interference of the operator, who, while one line is getting moulded, raised up, and distributed, calmly proceeds with the composition of the following one. Fig. 313i.—Matrices dropping into Magazine. The rate at which the work is produced is very great. One good operator with one machine can, it is said, turn out, hour by hour, matter that would be equivalent to two and a half pages of this book, arranged solid or without break. There are, of course, record performances of exceptional operators who have completed more than twice as much as this in a single hour. 653 Fig. 314.—Recording Anemometer. RECORDING INSTRUMENTS. Sir John Herschel, in enumerating at the close of his inestimable “Discourse on the Study of Natural Philosophy” the causes of the rapid development of the physical sciences in modern times, assigns a prominent place to the improvement of scientific apparatus, especially of those instruments by which exact measurements or observations are made. The accurate and elaborate instruments which serve for the delicate and precise determinations and observations of modern science require for their production a very advanced state of mechanical art, such as is indicated by the perfection of the tools we described in a former article; and these tools are themselves, on the other hand, the outcome of accurate knowledge, and another proof of the interaction between science and practical art. Since precise observations and accurate measurements form the essential bases of every science, its progress will be accelerated by every improvement in its instruments which increases their delicacy and exactness. Indeed, hardly any branch of knowledge becomes entitled to be called a science until it rests upon quantitative data of some kind. Chemistry was nothing but a confused collection of vague notions until the exact determinations of the balance were employed, and the proportions of the substances combining or separating in chemical actions were found to be related by certain simple and very definite laws. In all branches of inquiry there is the same necessity of quantitative comparisons: lengths, 654angles, surfaces, volumes, masses, durations must be compared with standards of their own kind; motions, forces, pressures, temperatures, lights must be measured. The case of chemistry shows the line along which other sciences are advancing. Physiology has made great strides since instruments of precision have been used in its investigations, and as some of these are of the kind we here propose to treat of, they will be described in the sequel. To recording instruments, meteorology is also largely indebted for the remarkable progress which it is making, and which will soon place this branch of knowledge in a condition to supply the most striking illustration of the difference between a science founded on accurate measurements and a mass of vague observations. The obvious advantage of a recording instrument (say, for example, such a one as that represented in Fig. 314, which registers the force and direction of the wind) is that the results are obtained without the immediate attention of an observer, and they can be continuously recorded at every instant, day and night; but there is another and yet greater advantage in certain kinds of instruments which write their own records, in the fact that they can be made to register results which would altogether escape direct observation. It is said that a practised astronomical observer will correctly record the time of a phenomenon to nearly the tenth of a second; but there are cases in which we may desire to estimate time to the thousandth part of a second or less. An investigation of M. Foucault has already been named in which a far less interval of time was concerned (page 387); but the recording instruments we have to mention here are of use for enabling us to make certain instantaneous actions mark the time of their occurrence with the greatest precision, and also for enabling us to note the variations in actions which are too rapid to be directly observed in their various phases. Fig. 315 is a diagram which will serve to explain the method in which the height of the barometer and the thermometer are registered in the ingenious metereograph, invented by Professor Hough, of Dudley Observatory. The contrivance has the advantage of performing the