ignorant to the most learned; and every person not only felt, but expressed the feeling, that a new pleasure had been added to their existence.

The pirated instruments, of course, were only of the simple form, and necessarily of rude and unscientific construction. They, however, had the effect of deeply injuring the property of the inventor; but the rage was soon over, and they were thrown aside as a pleasing but useless toy.

This, however, is not the case with the patent kaleidoscope, which is of great service in exhibiting an infinite variety of beautiful patterns, which are transferred to several of our manufactures. The system of endless changes is named as one of the most astonishing properties of the kaleidoscope. With a number of loose objects,-pieces of glass, for exampleit is impossible to reproduce any figure we have admired, when it is once lost; centuries may elapse before the same combination returns. If the objects, however, are placed in the cell so as to have very little motion, the same figure may be recalled; and, if absolutely fixed, the same pattern will return in every evolution of the object plate. A calculation of the number of forms is given upon the ordinary principles of combination-namely, that 24 pieces of glass may be combined 13917242888872552999425128493402200

times, an operation the performance of which would take hundreds of thousands of millions of years, even upon the supposition that twenty of them were performed every minute. This calculation, surprising as it appears, is false, not from being exaggerated, but from being far inferior to the reality. It proceeds upon the supposition that one piece of glass can exhibit only one figure, and that two pieces can exhibit only two figures; whereas it is obvious that two pieces, though they

can only be combined in two ways on the same straight line, yet the one can be put above and below the other, as well as on its right side or its left side, and may be joined so that the line connecting those centres may have an infinite number of positions with respect to an horizontal line.

CHARLES BABBAGE.

The calculating machines of the late Mr. Babbage have at different times excited much interest on the part of the public and of scientific men.

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"Mr. Babbage," says a writer in the Encyclopædia Britannica, was a fellow student at Cambridge with Sir John Herschel and Dean Peacock, and along with them contributed by his writings and personal efforts to introduce into that university the improved Continental mathematics.

"A few years after leaving college, he originated the plan of a machine for calculating tables by means of successive orders of differences; and having received for it in 1822 and the following year the support of the Astronomical and Royal Societies, and a grant of money from Government, he proceeded to its execution. It is believed that Mr. Babbage was the first who thought of employing mechanism for computing tables by means of differences: the machine was subsequently called the difference machine.'

"In the course of his proceedings, Mr. Babbage invented a mechanical notation (described in the Philosophical Transactions for 1826), intended to show the exact mutual relations of all the parts of any connected machine, however complex, at any given instant of time. He also made himself acquainted with the various machines used in the arts, with the tools used in constructing them, and with the details of the most

improved workshops. Employing Mr. Clements, a skilful mechanist, a portion of the calculating machine, very beautifully constructed, was brought into working order, and its success so far answered the expectations of its projector. But, notwithstanding several additional grants from Government, the outlay on this most expensive kind of work soon exceeded them. The part actually constructed is now placed in the museum of King's College, London. It employs numbers of nineteen digits, and effects summations by means of three orders of differences. Though only constituting a small part of the intended engine, it involves the principles of the whole. The inventor proposed to connect it with a printing apparatus, so that the engine should not only tabulate the numbers, but also print them beyond almost the possibility of error.

"At this stage (1834), Mr. Babbage contrived a machine of a far more comprehensive character, which he called the Analytical Machine, extending the plan so as to develop algebraic quantities, and to tabulate the numerical value of complicated functions when one or more of the variables which they contain are made to alter their values. Had this machine been constructed, it would necessarily have superseded what had already been done. Government were not unnaturally startled by this new proposal; and as about the same time Mr. Babbage's relations to Mr. Clements were broken off, the difficulties of the affair became insurmountable.

"The opinions of men of science are not unanimous as to the great practical importance of calculating tables by machinery; but the improvements of mechanical contrivance, which the joint skill of Mr. Babbage and Mr. Clements introduced into engineering workshops, are unquestionably of great importance to the arts."

Mr. Babbage was born in 1790, and died on the 18th of October, 1871. He was the author of several valuable works. One, "On the Economy of Manufactures and Machinery," published in 1832, has gone through several editions, and been translated into several languages. In it all mechanical processes are classified from the most scientific point of view, and the most interesting examples of the more important kinds of manufactures are described. In addition to this work, we may mention his "Comparative View of the different Life Assurance Societies," his "Differential and Integral Calculus," his "Decline of Science, A Ninth Bridgewater Treatise," and "The Exposition of 1851."

HENRY BESSEMER

The invention of the Bessemer process of decarburising pigiron while in a molten state, by blowing atmospheric air through it, and thereby producing steel, is an interesting story. Mr. Bessemer's discovery was in some measure accidental, like so many other discoveries in the arts. The remarkable thing is, that, taking into consideration the attention paid to the chemistry of metallurgy of late years, the discovery was not made long ago; and that it should have been reserved for Mr. Bessemer to make it, who was neither a chemist nor an iron manufacturer.

About 1856, says a writer in the Quarterly Review, the minds of inventors were running in the direction of improved guns. It was believed that these might be made much stronger if some better material than cast-iron were used; and Mr. Bessemer, like many others, began a series of experiments to solve the problem if he could. He first tried a mixture of castiron and cast-steel, the result being a half-decarbonised castiron. Guns made of this metal were found to possess great

strength; but as they were of comparatively small bore, 24pounders, Mr. Bessemer resolved to make them on a larger scale, for the purpose of more exclusively testing the strength of the material.

In the course of his experiments, the idea occurred to him that if he could contrive to blow air through melted pig-iron, he would be enabled to purify it to an unusual extent. He thought that, by thus bringing oxygen into contact with the fluid metal, the carbon with which it was surcharged would be removed, as well as the silicon, phosphorous, and sulphur which it contained. This is exactly what is done, after another and very laborious method, in the process of puddling. He proposed to reverse this process, and so get rid of puddling altogether. Instead of bringing the particles of the iron in turn into contact with the oxygen of the air, his scheme was to force the air through the fluid mass into contact with the separated particles of the iron. Now that the thing is done, we see how simple, how natural the first idea was. But it needs the quick intuition of genius to detect even simple things in practical science.

The only way of determining the matter was by putting the idea to the test of experiment. Accordingly, early in 1856, Mr. Bessemer ordered a stock of Blaenavon iron, and set up a blast-engine and cupola at Baxter House, St. Pancras, where he then resided.

The first apparatus which he used for conversion was a fixed cylindrical vessel three feet in diameter and four feet high, somewhat like an ordinary cupola furnace, lined with firebricks; and at some two inches from the bottom he inserted five 1.wyer pipes, with orifices about three-eighths of an inch in diameter. About half-way up was a hole for running in the