National Progress page 2

The attention of the British public was forcibly arrested by an able treatise on "Light," contributed by Sir John Herschel, in 1827, to the "Encyclopaedia Metropolitana." Its excellent method and lucid explanations attracted to the theory of Young and Fresnel men of science who had been deterred by the fragmentary and abstruse style of the former. This was followed four years later by a most able and precise mathematical exposition of the theory, and its application to optical problems, by Prof. Airy, who afterwards became astronomer royal. The writings of Prof. Airy and of Sir John Herschel have continued to be valuable sources of information on this subject, and on physical optics generally, not only in this country, but on the Continent.

While an impulse was thus given to the mathematical theory of light in the University of Cambridge, a similar progress was being made in the sister University of Dublin, where three of her most eminent professors - Sir William Rowan Hamilton, Dr. Lloyd, and Mr. M'Cullagh - devoted themselves energetically to its improvement and verification. Sir William Hamilton, a geometer of the first order, having undertaken a more completer discussion of the wave surface of Fresnel, to the equation of which he gave a more elegant form, ascertained the exact nature of that surface, and consequently the exact direction of refracted rays in the neighbourhood of the optic axes. The beautiful and unexpected results he obtained were verified by his friend Dr. Lloyd. The names of Sir W. Hamilton and Dr. Lloyd will be handed down to posterity in connection with this discovery. "But," says Professor Forbes, " they have other claims to our respect. The former has generalised the most complicated cases of common geometrical optics, by a peculiar analysis developed in his essays on 'Systems of Rays.' To Dr. Lloyd we are indebted foi several interesting experimental papers on optics, ior an impartial review of the progress of the science, and for an excellent elementary treatise on the wave theory, which forms by far the most popular introduction to the subject."

Closely associated in his pursuits as in personal friendship with Sir W. Hamilton and Dr. Lloyd was James M'Cullagh, a native of the County Tyrone, who died prematurely by his own hand in 1847, under the pressure of a fit of despondency brought on by excessive application to study, accompanied by neglect and imprudence in regard to his diet and to the laws of health. His unhappy end was greatly lamented, for he was equally beloved for his amiable and exemplary character, and admired for his genius. In the galaxy of illustrious names that shed light upon this age, not the least conspicuous is that of Mary Somerville, who is known in British science, not only as the able commentator of "La Place's Mécanique Céleste," but as the author of some ingenious experiments on the magnetising power of the violet ray, and on the permeability of different bodies to the chemical rays, similar to those of Melloni on the heating rays; and she found great and seemingly capricious variations in this respect. The beautiful invention of the stereoscope, one of the most interesting contributions made to the theory of vision, was the work of Mr. Wheatstone, who published an account of it in the "Philosophical Transactions" of 1838.

In connection with experiments of this class should be mentioned the invention of the daguerreotype, or the production of permanent pictures on plated copper, in 1825, which was brought to perfection in 1839 by Daguerre, whose name it bears. About the same time Hervey Fox Talbot applied himself to similar experiments, and invented the calotype, or the production of permanent pictures on paper; and by a subsequent invention he obtained what he justly called "an instantaneous process." An image was formed in a camera - a revolving wheel, 'to which was affixed a printed bill. The room being darkened, and the wheel made to revolve with the speed of 200 revolutions in a second, and being then illuminated by an electric spark, a legible impression of the printing was obtained. We doubt if in the whole history of physics a more astonishing result is recorded. Thus H. Fox Talbot, by his rare energy, brought his inventions almost to perfection. Numerous competitors of course appeared on the field, and obtained many interesting results. The talbotype was undoubtedly a great improvement on the daguerreotype process, which, besides requiring extraordinary care in the preparation of the plate, and in the process itself, demanded a costly material; but its great defect was the difficulty, if not impossibility, of rendering a paper surface suitable to the requirements of photography. Hence the use of a film of albumen on glass, by M. Niepce de St. Victor, in 1848, was a step considerably in advance; and still further progress was made by the use of collodion in the same way by M. le Gray, in 1850. By the employment of collodion, the process, from being one of extreme difficulty and uncertainty, became one that could be performed with great ease and certainty. An extraordinary increase of sensibility also was obtained by the use of this material, and thus the applications of photography were multiplied; and it is scarcely too much to assert that the employment of collodion in photography mainly led to that development of the art which has since taken place. Few, indeed, obtained satisfactory results with the daguerreotype, or even the albumen process; but with the collodion process, any one possessing an ordinary share of manipulative dexterity may obtain at pleasure either positive or negative pictures of great beauty. Many improvements have been introduced since the discovery of the applicability of collodion, but perhaps the most important has for its object the imparting to dry collodion some degree of that sensitiveness for which moist collodion is so remarkable, and thus making photography more generally useful, by rendering it easier to the traveller, or to the photographer who is obliged to operate at a distance from his studio. From these experiments in light has sprung the art of delineating the human features and all other objects with perfect accuracy, which has added greatly to the happiness of families, and created a great trade in photographic portraits, employing an immense number of persons, enriching many, and diffusing widely through the community a knowledge of public men, and a taste for the fine arts.

But far more important are the wondrous powers evolved from the study of heat. The pioneer in this branch among us was the Hon. H. Cavendish, who was born in 1731, and devoted his life to the pursuits of science. He was followed by Dalton, who made several important discoveries in chemistry, particularly with reference to the gases, and in the doctrine of heat. Sir Humphry Davy has remarked that Dalton laboured for more than a quarter of a century with the most disinterested views. With the greatest modesty and simplicity of character, be has remained in the obscurity of the country, neither asking for approbation nor offering himself as an object of applause. In 1833, at the age of sixty-seven, he received a pension from government, which he enjoyed till 1844, when he died. His discoveries may be said to have terminated at the age of forty, though he laboured for thirty years after. The conceptive faculty seems to have spent itself in his earlier efforts. His discoveries in connection with heat, electricity, and magnetism, and their practical applications, in connection with which are those of Sir Humphry Davy, Dr. Faraday, General Sir E. Sabine, and Captain Sir J. C. Ross, are too familiar to our readers to be dwelt upon here, especially as their full development belongs to a subsequent period.

We shall now note some points of contact between science and the mechanical arts, in the progress of those discoveries and inventions which have so wonderfully increased the power of man in the present age. One of the most important of these is the power of calculating the strength of materials, to which we owe the tubular bridge, and with which the name of Robert Stephenson is so honourably connected. The comparatively great strength of tubes was a fact known from the time of Galileo, but it was left for Robert Stephenson to bring th

Like the Herschels, the two Stephensons attained almost equal celebrity. George, the father, was born near Newcastle, in 1781. His parents being very poor, he was obliged at an early age to gain a subsistence by working at coal-pits; but after a while he rose to be an engine-man, when his wages became twelve shillings a week, and his ingenuity and attention soon gained him the confidence of his employers. By working extra hours, in repairing the watches and clocks of his neighbours, he managed to give his son Robert the education of which he himself had felt the want; for he derived his knowledge of machinery from observation, and not from books. He turned his attention to the invention of a safety lamp, in which he made considerable progress, and at length produced it almost simultaneously with that of Sir H. Davy, who was occupied on the same subject. Attempts had been made for some time to introduce locomotives generally, but engineers had bewildered themselves in the endeavour to overcome an imaginary difficulty. Without making a trial, they supposed that the adhesion between the wheels and the rails was not sufficient to render propulsion possible, except with the aid of complicated apparatus. Stephenson saw that this supposition had no foundation, and therefore he succeeded where they had failed. Among the many improvements he introduced into the locomotive, increasing the draft, by throwing the waste steam into the chimney, was not the least valuable. He conceived the idea, also, of a velocity on railways much higher than had before been thought of, and he attained it. In a competition, in 1829, an engine made by him gained the prize; and his success was due, in a great degree, to his application of a principle which was not unknown, but had never before been reduced to practice - the increase of evaporating power in the boiler, by conveying the hot air from the furnace to the smoke-box through a number of tubes. He may be said to have been to the locomotive what Watt was to the fixed engine. He died in 1848. Robert Stephenson, his son, was born in 1803. Notwithstanding the poverty of his parents, he was well educated, thanks to his father's exertions, which were well seconded by his own. Having spent some time in the University of Edinburgh, where he gained a prize in mathematics, he was first placed in his father's factory, and then was sent out to South America, to report on the gold and silver mines of Columbia and Venezuela. On his return he devoted himself to the improvement of locomotives, made various important experiments, and greatly assisted his father in his projects. He subsequently constructed numerous railways, many of which included works of great difficulty, and several of them were on the Continent, where his skill was fully appreciated. He gave to iron bridges a span greater than had ever before been attempted; but his fame mainly rests on his invention of the tubular bridge, though, in carrying out this idea, he had the advantage of very able assistance. Besides those at the Menai Straits, he constructed the tubular bridge over the St. Lawrence, at Montreal, where it is nearly two miles wide. He was elected member of Parliament; and he died in 1859, having, it is said, refused a title, which could, indeed, have added nothing to the brilliancy of that name which he and his father had rendered so celebrated.

Sir M. Brunei, another of the heroes of mechanical science, made a great step in advance by the invention of self-acting machinery to supersede the work of artisans, by which a new epoch was created in art. By means of this machinery, not only is it possible to execute, in a comparatively short time, and with a prodigious economy, such objects as blocks and pulleys - which are required in vast numbers, and should be precisely alike - but the accuracy of the manufacture is thereby increased, and works which transcend the power of unaided muscular labour, such as an iron steam cylinder, eight feet or more in diameter, may be readily executed under the direction of a very ordinary workman by means of steam-power and self-acting machinery. He was aided by the Government in starting a manufactory for the construction of tools, for which he received £53,000. In the course of a year 140,000 blocks, on no less than 200 different patterns, were produced, and the number of workmen was diminished in the proportion of about eleven to one. As his reward, Brunei received £16,000, being two-thirds of the first year's saving - a sufficient proof that he was the bona fide inventor of this admirable apparatus. Nearly twenty years elapsed before such a splendid example of ingenious economy and artistic precision was generally imitated; yet before his death Sir Mark Brunei saw the fruit of his ingenuity almost indefinitely multiplied in the workshops of London, Manchester, Birmingham, Glasgow, and Newcastle, and no less highly appreciated and extensively employed abroad. "The more we reflect," says Professor Forbes, " on the comparative state of the arts now and a century ago, the more we shall find reason to estimate highly the introduction of correct and scientific ideas of machinery and tools, for constructing other machines and structures. It was, in fact, the necessary complement of the invention of the steam-engine. Watt contrived the mighty heart which was to give a new impulse to social life: Brunei and others of the same stamp added limbs and muscles, whereby its energies were rendered thoroughly practical." Among these may be mentioned the planing machine, the circular saw, and the mortising machine, and, above all, perhaps, the steam-hammer, which form the staple of the magnificent and varied apparatus with which, driven by the gigantic power of steam, our mechanical factories are now so generally provided, and without which the triumphs of art in which our generation glories - our railroads, our locomotives, our crystal palaces, our tunnels, suspension bridges, and our steam navies - would have been impossible achievements. The greatest effort of Brunei was the Thames Tunnel, a structure of perfect firmness and solidity laid on a quicksand, and forced through a quaking mass of mud, which will endure like the cloacx of regal Rome, when the palace and the cathedral have crumbled to dust. He was enabled to accomplish this prodigious work by means of " the shield " - a movable vertical frame of cast iron, provided with thirty-six cells, in each of which a man was placed with a pick to excavate the area, this frame or shield being moved bodily forwards by powerful screws, while the bricklayers brought up the arched masonry behind, which was then beyond the power of injury. The works, however, were several times "drowned" during their progress by the irruptions of the Thames, but every fresh difficulty was met successfully by the heroic engineer. The tunnel was commenced on the 2nd of March, 1825, and finished on the 25th of March, 1843. Brunei survived the completion of this, his greatest work, above six years, dying on the 12th of December, 1849. He was the chief of a class - the mechanical engineers - since extensively multiplied: and he left a son to be the brightest ornament of the same profession, and to add fresh lustre to his name.