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A LECTURE

ON THE

PROGRESS OF PHYSICAL SCIENCE

SINCE THE OPENING OF

THE LONDON INSTITUTION.

To extend the range of human knowledge-to place within the grasp of the many, means of its acquisition originally confined to the few-to diffuse a taste for the exercise of the higher faculties with which man is endowed-to transmit, orally and experimentally, the researches of minds, mortal as to their material conjunction, immortal in their effect upon their fellow man-to stand the noblest cenotaphs of genius, the perdurable links which bind it to surviving kindred:—are among the lofty aims of Literary and Scientific Institutions.

If we are not biassed by national vanity in considering London the metropolis of the civilised world-the Institution in which we are at present assembled, THE LONDON INSTITUTION Should occupy a high post among the Scientific bodies of Europe.

By means of such Establishments, and through the support given to them by a public which prefers the more enduring and refined gratifications educed by the cultivation of intellect, to the transient, dear-bought pleasures of indolent sensuality;—by means of such endowments and such coadjutors,

Science and Literature have lately marched with rapidlyaccelerated strides and it is their progress within the period of Twenty-two years, that I am this evening to sketch.

Vast, indeed is the field; and to lead you step by step over its surface, to cull with you its varied flowers, in the limited time allotted to me is impossible: fortunate I shall be if the omissions I am compelled to make be considered by you as of less importance than the discoveries which I enumerate; but most difficult is it to estimate the comparative importance of results where all are important, all valuable, all conducive to the general weal.

In the year 1815 the First stone of this Institution was laid; in the year 1819 the last and in that year an Introductory Discourse was given on the opening of this Theatre by Mr. Brande. From that Discourse we will take date, and examine, as succinctly as our time will permit, the most notable discoveries which have been made since that period; many of which have wrought epochal changes in our knowledge, and will work gradual changes in our political history.

Physical Science treats of Matter, and what I shall tonight term its Affections; namely, Attraction, Motion, Heat, Light, Electricity, Magnetism, Chemical-Affinity. When these re-act upon matter they constitute Forces. The present tendency of theory seems to lead to the opinion that all these Affections are resolvable into one, namely, Motion: however, should the theories on these subjects be ultimately so effectually generalised as to become laws, they cannot avoid the necessity for retaining different names for these different Affections; or, as they would then be called, different Modes of Motion. To the Sciences which treat of these various material forces, are given the various titles of Mechanics, Thermotics, Optics, Electricity, Magnetism, Chemistry, Crystallography; and from the united effects of some or other of these, are derived the Composite-Sciences, Geology, Meteorology, and Astronomy. In the very brief sketch which I can on this occasion give you of the recent Progress of Physical Discovery, I shall confine myself to the Inorganic Sciences I shall, therefore, not touch upon Botany, Zoo

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logy, nor Anatomy, the norma of organised matter. My apology for this is the absolute necessity of stopping somewhere, of placing some limit to the exhaustless space toward which the mind expands when not restrained within the bounds of conventional classification, "the pales and forts of reason:" thus were I to enter the field of organised being, I should again find myself gradually led over to the scarcedefinable boundary which separates Physics from Metaphysics; things apparently remote and distinct become, when curiously pursued, unavoidably connected and inseparate: were our time unlimited, the effort must be made; how much more so when it is dwindled to so short a span as that appropriated to a single lecture.

MECHANICS, the Science of Motion, the first-born of the Sciences, claims our primary attention. Here a most beneficial change has latterly been apparent: laws which, divested of their invariable co-agents, were formerly viewed solely in their abstract relations, have lately been studied by a high order of minds in their state of actual development, and with a view to their practical application. Theory, mathematical-analysis, and experiment, have marched hand in hand, and the labours of Navier and Poncelet have marked an epoch in Mechanical Science, and cleared the grass-grown path originally opened by Coulomb.

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Navier in 1826 published a work entitled "Resumé ďun Cours de Construction", in which he undertook the discussion of mechanical problems, taking into consideration all their practical conditions. He has there treated at large of the strength of materials in wood and iron, and of the principal and more simple structures formed with these materials. In 1830 appeared the "Mécanique Industrielle" of Poncelet, a work which is considered by high authorities to have almost created the Science of Practical Mechanics; and which is not more valuable for the great general interest and importance of its results, than for the simplicity and elegance of the deductions by which they are attained. Poncelet has moreover applied these deductions with great success to water-wheels,

the construction of float-boards, and the proper curve to be given to them: by great perseverance he has succeeded in introducing his improvements generally throughout France, where, from the absence of coal-fuel, water-power is of far more value than with us. Undershot and breast-wheels of his construction yield, when compared with those of the old form, one-third more power with the same expense of water. The experiments of Morin, a pupil of Poncelet, made at the cost of the French Government, have given to our knowledge of the effects of friction a high degree of precision and certainty.

In this country Professor Willis has contributed to advance Mechanics by a systematic classification, and has established the mathematical relation of the velocities of the different moving parts of machines. Professor Moseley has recently published a paper, in which he lays down rules for the determination of what he calls "the Modulus" of a machine. This term I will endeavor to explain to you. In every machine there are four mechanical elements :-first, the work done by the motive power upon the driving points: secondly, that expended upon the working points, that is those parts of the machine where the original motive power is utilised: thirdly, the work wasted or expended upon the prejudicial resistences, such as friction, aërial-opposition, etc.: and fourthly, that accumulated in the moving elements; as for instance in a fly-wheel, where the power impressed by the machine when in its most advantageous mechanical situation is accumulated, and again evolved when the initial power decreases. Between these four elements there exists a relation, which is always the same for the same machine, and different for different machines; this relation is what Mr. Moseley calls "the Modulus”, and this relation he determines for simple and compound machines.

I may not, on the present occasion, experimentally elucidate to you the various practical improvements which machines have undergone during the period we are considering, but we need little experiment when a daily survey of the now-familiar arts must force on the mind a conviction of

the rapid advance which this Science has recently made, whereby its influence on civilisation is increased to an extent unequalled by many if not by any of the other Sciences. Perhaps the grandest mastery of mind over matter, the greatest result of mechanical power, is evinced in the railroad locomotive-machines which convey us with such rapidity that, if the notion be correct which considers time to be only a succession of events, we may, compared with our ancestors, be said to live two lives in one; but so unperceived is the onward march of Science, that we marvel not at what a few years back would have been deemed a miracle: the steps by which we advance are so numerous, that we note not the height to which we have mounted; the rock is worn away and we count not the drops of water which have hollowed it.

Another strange mechanical power has been educed by the labours of Mr. Babbage and others, by which the hand is made to do the work of the mind; by which calculations requiring much study, much activity of thought, much strained attention-more perhaps than any single intellect could bring to bear-can be wrought by turning a winch or pressing a treadle. Mr. Babbage has devised and partly constructed two machines for calculating and printing astronomical tables; the first would employ 120 figures, the second 4000: the latter would calculate the numerical value of any algebraic fraction, and, at any executory period previously fixed on, would cease to tabulate that and commence a different one. These machines have never been completed, from the enormous expense attendant upon their construction; enough however has been done to establish the practicability of them, and no doubt can rest on the minds of those who have duly considered the subject, that expense alone is the barrier to attaining by these means any degree of arithmetical perfection.

For performing the more simple calculations of addition, subtraction, multiplication, and division, two instruments, invented I believe by Dr. Roth, have lately been exhibited in this city. They occupy very little space; the one being a circle of about a foot in diameter, the other an oblong of

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