PG54897.B00524
(385.) Perhaps it may be truly remarked, that, next to the establishment of institutions having either the promotion of science in general, or, what is still more practically efficacious in its present advanced state, that of particular departments of physical enquiry, for their express objects, nothing has exercised so powerful an influence on the progress of modern science as the publication of monthly and quarterly scientific journals, of which there is now scarcely a nation in Europe which does not produce several. The quick and universal circulation of these, places observers of all countries on the same level of perfect intimacy with each other’s objects and methods, while the abstracts they from time to time (if well conducted) contain of the most important researches of the day consigned to the more ponderous tomes of academical collections, serve to direct the course of general observation, as well as to hold out, in the most conspicuous manner, models for emulative imitation. In looking forward to what may hereafter be expected from this cause of improvement, we are not to forget the powerful effect which must in future be produced by the spread of elementary works and digests of what is actually known in each particular branch of science. Nothing can be more discouraging to one engaged in active research, than the impression that all he is doing may, very likely, be labour taken in vain; that it may, perhaps, have been already done, and much better done, than, with his opportunities, or his resources, he can hope to perform it; and, on the other hand, nothing can be more exciting than the contrary impression. Thus, by giving a connected view of what has been done, and what remains to be accomplished in every branch, those digests and bodies of science, which from time to time appear, have, in fact, a very important weight in determining its future progress, quite independent of the quantity of information they communicate. With respect to elementary treatises, it is needless to point out their utility, or to dwell on the influence which their actual abundance, contrasted with their past remarkable deficiency, is likely to exercise over the future. It is only by condensing, simplifying, and arranging, in the most lucid possible manner, the acquired knowledge of past generations, that those to come can be enabled to avail themselves to the full of the advanced point from which they will start.

PG54897.B00525
(386.) One of the means by which an advanced state of physical science contributes greatly to accelerate and secure its further progress, is the exact knowledge acquired of physical data, or those normal quantities which we have more than once spoken of in the preceding pages (222.); a knowledge which enables us not only to appretiate the accuracy of experiments, but even to correct their results. As there is no surer criterion of the state of science in any age than the degree of care bestowed, and discernment exhibited, in the choice of such data, so as to afford the simplest possible grounds for the application of theories, and the degree of accuracy attained in their determination, so there is scarcely any thing by which science can be more truly benefited than by researches directed expressly to this object, and to the construction of tables exhibiting the true numerical relations of the elements of theories, and the actual state of nature, in all its different branches. It is only by such determinations that we can ascertain what changes are slowly and imperceptibly taking place in the existing order of things; and the more accurate they are, the _sooner_ will this knowledge be acquired. What might we not now have known of the motions of the (so-called) fixed stars, had the ancients possessed the means of observation we now possess, and employed them as we employ them now?

PG54897.B00526
(387.) In any enumeration of causes which have contributed to the recent rapid advancement of science, we must not forget the very important one of improved and constantly improving means of observation, both in instruments adapted for the exact measurement of quantity, and in the general convenience and well-judged adaptation to its purposes, of every description of scientific apparatus. In the actual state of science there are few observations which can be productive of any great advantage but such as afford accurate measurement; and an increased refinement in this respect is constantly called for. The degree of delicacy actually attained, we will not say in the most elaborate works of the highest art, but in such ordinary apparatus as every observer may now command, is such as could not have been arrived at unless in a state of the mechanical arts, which in its turn (such is the mutual re-action of cause and effect) requires for its existence a very advanced state of science. What an important influence may be exercised over the progress of a single branch of science by the invention of a ready and convenient mode of executing a definite measurement, and the construction and common introduction of an instrument adapted for it cannot be better exemplified than by the instance of the reflecting goniometer. This simple, cheap, and portable little instrument, has changed the face of mineralogy, and given it all the characters of one of the exact sciences.

PG54897.B00527
(388.) Our means of perceiving and measuring minute quantities, in the important relations of weight, space, and time, seem already to have been carried to a point which it is hardly conceivable they should surpass. Balances have been constructed which have rendered sensible the millionth part of the whole quantity weighed; and to turn with the thousandth part of a grain is the performance of balances pretending to no very extraordinary degree of merit. The elegant invention of the sphærometer, by substituting the sense of touch for that of sight in the measurement of minute objects, permits the determination of their dimensions with a degree of precision which is fully adequate to the nicest purposes of scientific enquiry. By its aid an inch may be readily subdivided into ten or even twenty thousand parts; and the lever of contact, an instrument in use among the German opticians, enables us to appretiate quantities of space even yet smaller. For the subdivision of time, too, the perfection of modern mechanism has furnished resources which leave very little to be desired. By the aid of clocks and chronometers, as they are now constructed, a few tenths of a second is all the error that need be apprehended in the subdivision of a day; and for the further subdivision of smaller portions of time, instruments have been imagined which admit of almost unlimited precision, and permit us to appreciate intervals to the nicety of the hundredth, or even the thousandth part of a single second.[59] When the precision attainable by such means is contrasted with what could be procured a few generations ago, by the rude and clumsy workmanship of even the early part of the last century, it will be no matter of astonishment that the sciences which depend on exact measurements should have made a proportional progress. Nor will any degree of nicety in physical determinations appear beyond our reach, if we consider the inexhaustible resources which science itself furnishes, in rendering the quantities actually to be determined by measure great multiples of the elements required for the purposes of theory, so as to diminish in the same proportion the influence of any errors which may be committed on the final results.

PG54897.B00528
(389.) Great, indeed, as have been of late the improvements in the construction of instruments, both as to what regards convenience and accuracy, it is to the discovery of improved _methods_ of observation that the chief progress of those parts of science which depend on exact determinations is owing. The balance of torsion, the ingenious invention of Cavendish and Coulomb, may be cited as an example of what we mean. By its aid we are enabled not merely to render sensible, but to subject to precise measurement and subdivision, degrees of force infinitely too feeble to affect the nicest balance of the usual construction, even were it possible to bring them to act on it. The galvanometer, too, affords another example of the same kind, in an instrument whose range of utility lies among electric forces which we have no other means of rendering sensible, much less of estimating with exactness. In determinations of quantities less minute in themselves, the methods devised by Messrs. Arago and Fresnel, for the measurement of the refractive powers of transparent media by means of the phenomenon of diffraction, may be cited as affording a degree of precision limited only by the wishes of the observer, and the time and patience he is willing to devote to his observation. And in respect of the direction of observations to points from which real information is to be obtained, and positive conclusions drawn, the hygrometer of Daniell may be cited as an elegant example of the introduction into general use of an instrument substituting an indication founded on strict principles for one perfectly arbitrary.

PG54897.B00529
(390.) In speculating on the future prospects of physical science, we should not be justified in leaving out of consideration the probability, or rather certainty, of the occasional occurrence of those happy accidents which have had so powerful an influence on the past; occasions, where a fortunate combination opportunely noticed may admit us in an instant to the knowledge of principles of which no suspicion might occur but for some such casual notice. Boyle has entitled one of his essays thus remarkably,--“_Of Man’s great Ignorance of the Uses of natural Things; or that there is no one Thing in Nature whereof the Uses to human Life are yet thoroughly understood_.”[60] The whole history of the arts since Boyle’s time has been one continued comment on this text; and if we regard among the uses of the works of nature, _that_, assuredly the noblest of all, which leads us to a knowledge of the Author of nature through the contemplation of the wonderful means by which he has wrought out his purposes in his works, the sciences have not been behind hand in affording their testimony to its truth. Nor are we to suppose that the field is in the slightest degree narrowed, or the chances in favour of such fortunate discoveries at all decreased, by those which have already taken place: on the contrary, they have been incalculably extended. It is true that the ordinary phenomena which pass before our eyes have been minutely examined, and those more striking and obvious principles which occur to superficial observation have been noticed and embodied in our systems of science; but, not to mention that by far the greater part of natural phenomena remain yet unexplained, every new discovery in science brings into view whole classes of facts which would never otherwise have fallen under our notice at all, and establishes relations which afford to the philosophic mind a constantly extending field of speculation, in ranging over which it is next to impossible that he should not encounter new and unexpected principles. How infinitely greater, for instance, are the mere chances of discovery in chemistry among the innumerable combinations with which the modern chemist is familiar, than at a period when two or three imaginary elements, and some ten or twenty substances, whose properties were known with an approach to distinctness, formed the narrow circle within which his ideas had to revolve? How many are the instances where a new substance, or a new property, introduced into familiar use, by being thus brought into relation with all our actual elements of knowledge, has become the means of developing properties and principles among the most common objects, which could never have otherwise been discovered? Had not platina (to take an instance) been an object of the most ordinary occurrence in a laboratory, would a suspicion have ever occurred that a lamp could be constructed to burn without flame; and should we have ever arrived at a knowledge of those curious phenomena and products of semi-combustion which this beautiful experiment discloses?

PG54897.B00530
(391.) Finally, when we look back on what has been accomplished in science, and compare it with what remains to be done, it is hardly possible to avoid being strongly impressed with the idea that we have been and are still executing the labour by which succeeding generations are to profit.[61] In a few instances only have we arrived at those general axiomatic laws which admit of direct deductive inference, and place the solutions of physical phenomena before us as so many problems, whose principles of solution we fully possess, and which require nothing but acuteness of reasoning to pursue even into their farthest recesses. In fewer still have we reached that command of abstract reasoning itself which is necessary for the accomplishment of so arduous a task. Science, therefore, in relation to our faculties, still remains boundless and unexplored, and, after the lapse of a century and a half from the æra of Newton’s discoveries, during which every department of it has been cultivated with a zeal and energy which have assuredly met their full return, we remain in the situation in which he figured himself,--standing on the shore of a wide ocean, from whose beach we may have culled some of those innumerable beautiful productions it casts up with lavish prodigality, but whose acquisition can be regarded as no diminution of the treasures that remain.

PG54897.B00531
(392.) But this consideration, so far from repressing our efforts, or rendering us hopeless of attaining any thing intrinsically great, ought rather to excite us to fresh enterprise, by the prospect of assured and ample recompense from that inexhaustible store which only awaits our continued endeavours. “It is no detraction from human capacity to suppose it incapable of infinite exertion, or of exhausting an infinite subject.”[62] In whatever state of knowledge we may conceive man to be placed, his progress towards a yet higher state need never fear a check, but must continue till the last existence of society.

PG54897.B00532
(393.) It is in this respect an advantageous view of science, which refers all its advances to the discovery of general laws, and to the inclusion of what is already known in generalizations of still higher orders; inasmuch as this view of the subject represents it, as it really is, essentially incomplete, and incapable of being fully embodied in any system, or embraced by any single mind. Yet it must be recollected that, so far as our experience has hitherto gone, every advance towards generality has at the same time been a step towards simplification. It is only when we are wandering and lost in the mazes of particulars, or entangled in fruitless attempts to work our way downwards in the thorny paths of applications, to which our reasoning powers are incompetent, that nature appears complicated:--the moment we contemplate it as it is, and attain a position from which we can take a commanding view, though but of a small part of its plan, we never fail to recognise that sublime simplicity on which the mind rests satisfied that it has attained the truth.

PG54897.B00533
INDEX.

PG54897.B00534
Acoustics cultivated by Pythagoras and Aristotle, page 248.

PG54897.B00535
Æpinus, his laws of equilibrium of electricity, 332.

PG54897.B00536
Aëriform fluids, liquids kept in a state of vapour, 321.

PG54897.B00537
Agricola, George, his knowledge of mineralogy and metallurgy, 112.

PG54897.B00538
Air, compressibility and elasticity of; limitation to the repulsive tendency of, 226. Weight of, unknown to the ancients, 228. First perceived by Galileo, 228. Proved by a crucial instance, 229. Equilibrium of, established, 231. Dilatation of, by heat, 319.

PG54897.B00539
Air-pump, discovery of, 230.

PG54897.B00540
Airy, his experiments in Dolcoath mine, 187.

PG54897.B00541
Alchemists, advantages derived from, 11.

PG54897.B00542
Algebra, 19.

PG54897.B00543
Ampere, his electro-dynamic theory, 202. Utility of, 203, 324.

PG54897.B00544
Analysis of force, 86. Of motion, 87. Of complex phenomena, 88.

PG54897.B00545
Anaxagoras, philosophy of, 107.

PG54897.B00546
Animal electricity, 337.

PG54897.B00547
Arago, M., his experiment with a magnetic needle and a plate of copper, 157.

PG54897.B00548
Archimedes, his practical application of science, 72. His knowledge of hydrostatics, 231.

PG54897.B00549
Arfwedson, his discovery of lithia, 158.

PG54897.B00550
Aristotle, his knowledge of natural history, 109. His works condemned, and subsequently studied with avidity, 111. His philosophy overturned by the discoveries of Copernicus, Kepler, and Galileo, 113.

PG54897.B00551
Arithmetic, 19.

PG54897.B00552
Art, empirical and scientific, differences between, 71. Remarks on the language, terms, or signs, used in treating of it, 70.

PG54897.B00553
Assurances, life, utility and abuses of, 58.

PG54897.B00554
Astronomy, cause of the slow progress of our knowledge of, 78. Theory and practical observations distinct in, 132. An extensive acquaintance with science and every branch of knowledge necessary to make a perfect observer in, 132. Five primary planets added to our system, 274. Positions, figures, and dimensions of all the planetary orbits now well known, 275.

PG54897.B00555
Atomic theory, 305. Advantage of, 306.

PG54897.B00556
Atomic weights of chemical elements, 306.

PG54897.B00557
Attraction, capillary, or capillarity, investigated by Laplace and Young, 234.

PG54897.B00558
Bacon, celebrated in England for his knowledge of science, 72. Benefits conferred on Natural Philosophy by him, 104. His Novum Organum, 105. His reform in philosophy proves the paramount importance of induction, 114. His prerogative of facts, 181. Illustrated by the fracture of a crystallized substance, 183. His collective instances, 184. Importance of, 185. His experiment on the weight of bodies, 186. Travelling instances of, frontier instances of, 188. His difference between liquids and aëriform fluids, 233.

PG54897.B00559
Bartolin, Erasmus, first discovers the phenomena exhibited by doubly refracting crystals, 254.

PG54897.B00560
Beccher, phlogistic doctrines of, 300.

PG54897.B00561
Bergmann, his advancement in crystallography, 239.

PG54897.B00562
Bernoulli, experiments of, in hydrodynamical science, 181.

PG54897.B00563
Biot, his hypothesis of a rotatory motion of the particles of light about their axes, 262.

PG54897.B00564
Black, Dr., his discovery of latent heat, 322.

PG54897.B00565
Bode, his curious law observed in the progression of the magnitudes of the several planetary orbits, 308.

PG54897.B00566
Bodies, natural constitution of, 221. Division of, into crystallized and uncrystallized, 242.

PG54897.B00567
Bones, dry, a magazine of nutriment, 65.

PG54897.B00568
Borda, his invention for subdivision, 128.

PG54897.B00569
Botany, general utility of, 345.

PG54897.B00570
Boyle, Robert, his enthusiasm in the pursuit of science, 115. His improvement on the air-pump, 230.

PG54897.B00571
Brain, hypothesis of its being an electric pile, 343.

PG54897.B00572
Bramah’s press, principle and utility of, 233.

PG54897.B00573
Brewster, Dr., his improvement on lenses for lighthouses, 56. His researches prove that the phenomena exhibited by polarized light, in its transmission through crystals, afford a certain indication of the most important points relating to the structure of crystals themselves, 263.

PG54897.B00574
Cabot, Sebastian, his discovery of the variation of the needle, 327.

PG54897.B00575
Cagnard, Baron de la Tour, utility of his experiments, 234.

PG54897.B00576
Causes and consequences directors of the will of man, 6.

PG54897.B00577
Causes, proximate, discovery of, called by Newton _veræ causæ_, 144.

PG54897.B00578
Celestial mechanics, 265.

PG54897.B00579
Chaldean records, 265.

PG54897.B00580
Chemistry furnishes causes of sudden action, also fulminating compositions, 62. Analogy of the complex phenomena of, with those of physics, 92. Benefits arising from the analysis of, 94. Axioms of, analogous to those of geometry, 95. Many of the new elements of, detected in the investigation of residual phenomena, 158. The most general law of, 209. Illustration of, 210. Between fifty and sixty elements in, 211. Objects of, 296. General heads of the principal improvements in, 302. Remarks on those general heads, 304.

PG54897.B00581
Chemistry, Stahlian, cause of the mistakes and confusions of, 123.

PG54897.B00582
Chladni, experiments of, in dynamical science, 181.

PG54897.B00583
Chlorine, disinfectant powers of, 56.

PG54897.B00584
Clarke, Dr., his experiments on the arseniate and phosphate of soda, 170. His success in producing a new phosphate of soda, 171.

PG54897.B00585
Climate, change of, in large tracts of the globe, alleged cause of, 145.

PG54897.B00586
Coals, power of a bushel of, properly consumed, 59. Quantity consumed in London, 60.

PG54897.B00587
Cohesion, an ultimate phenomenon, 90.

PG54897.B00588
Cold, qualities of, 318.

PG54897.B00589
Compass, mariner’s, 55.

PG54897.B00590
Condensation, a source of heat, 313.

PG54897.B00591
Conduction of heat, laws of, 205.

PG54897.B00592
Copernicus, effect of his discoveries on the Aristotelian philosophy, 113. Objections to his astronomical doctrines, 269.

PG54897.B00593
Crystallography, laws of, 123, 239. A determinate figure supposed to be common to all the particles of a crystal, 242.

PG54897.B00594
D’Alembert, his improvements in hydrodynamics, 236.

PG54897.B00595
Dalton, his announcement of the atomic theory, 305. His examination of gases and vapours, 319.

PG54897.B00596
Davy, Sir H., brings the voltaic pile to bear upon the earths and alkalies, 339.

PG54897.B00597
Deduction, utility of, 174.

PG54897.B00598
De l’Isle, Romé, his study of crystalline bodies, 239.

PG54897.B00599
Dew, causes of, investigated, 159. Effects of, on different substances, 160. Objects capable of contracting it, 161. A cloudless sky favourable to its production, 162. General proximate cause of, 163.

PG54897.B00600
Drummond, lieutenant, his improvement on lenses for lamps of lighthouses, 56.

PG54897.B00601
Dynamics, importance of, 96, 223.

PG54897.B00602
Earth, the orbit of,--diminution of its eccentricity round the sun, 147.

PG54897.B00603
Economy, political, 73.

PG54897.B00604
Egypt, great pyramid of, height, weight, and ground occupied by it, 60. Accuracy of the astronomical records of, 265.

PG54897.B00605
Elasticity, an ultimate phenomenon, 90.

PG54897.B00606
Electricity may be the cause of magnetism, 93. Universality of, 329. Effects of, 330. Activity of, 331. Equilibrium of, 332. Productive of chemical decomposition, 338.

PG54897.B00607
Empirical laws, 178. Evils resulting from, 179.

PG54897.B00608
Encke, professor, his prediction of the return of the comet so many times in succession, 156.

PG54897.B00609
Englefield, sir H., his analysis of a solar beam, 314.

PG54897.B00610
Equilibrium maintained by force, 222.

PG54897.B00611
Erman, professor, his opinion of the effects of the voltaic circuit, 340.

PG54897.B00612
Euler, his improvement on Newton’s theory of sound, 247.

PG54897.B00613
Experience, source of our knowledge of nature’s laws, 76.

PG54897.B00614
Experiment, a means of acquiring experience, 76. Utility of, 151.

PG54897.B00615
Facts, the observation of, 118.

PG54897.B00616
Faujas de St. Fond, imaginary craters of, 131.

PG54897.B00617
Fluids, laws of the motion of, 181. Compressibility of, 225. Consideration of the motions of, more complicated than that of equilibrium, 235.

PG54897.B00618
Force, analysis of, 86. The cause of motion, 149. Phenomena of, 221. Molecular forces, 245.

PG54897.B00619
Fourier, baron, his opinion that the celestial regions have a temperature, independent of the sun, not greatly inferior to that at which quicksilver congeals, 157. His analysis of the laws of conduction and radiation of heat, 317.

PG54897.B00620
Franklin, Dr., his experiments on electricity, 332.

PG54897.B00621
Fresnel, M., his mathematical explanation of the phenomena of double refraction, 32. His improvement on lenses for lamps of lighthouses, 56. His opinions on the nature of light, 207. His experiments on the interference of polarized light, 261. His theory of polarization, 262.

PG54897.B00622
Friction, a source of heat, 313.

PG54897.B00623
Galileo, celebrity of, for his knowledge of science, 72. His exposition of the Aristotelian philosophy, 110. His refutation of Aristotle’s dogmas respecting motion, his persecution in consequence of it, 113. His knowledge of the accelerating power of gravity, 168. His knowledge of the weight of the atmosphere, 228.

PG54897.B00624
Galvani, utility of his discoveries in electricity, 335. His application of it to animals, 336.

PG54897.B00625
Gay-Lussac, his examination of gases and vapours, 319.

PG54897.B00626
Generalization, inductive, 1, 90.

PG54897.B00627
Geology, 281. Its rank as a science, 287.

PG54897.B00628
Geometry, axioms of, an appeal to experience, not corporeal, but mental, 95.

PG54897.B00629
Gilbert, Dr., of Colchester, his knowledge of magnetism and electricity, 112.

PG54897.B00630
Gravitation, law of, a physical axiom of a very high and universal kind, 98. Influence of, decreases in the inverse ratio of the square of the distance, 123.

PG54897.B00631
Greece, philosophers of, their extraordinary success in abstract reasoning, and their careless consideration of external nature, 105. Their general character, 106. Philosophy of, 108.

PG54897.B00632
Grimaldi, a jesuit of Bologna, his discovery of diffraction, or inflection of light, 252.

PG54897.B00633
Guinea and feather experiment, 168.

PG54897.B00634
Gunpowder, invention of, 55. A mechanical agent, 62.

PG54897.B00635
Haarlem lake, draining of, 61.

PG54897.B00636
Harmony, sense of, 248.

PG54897.B00637
Head, captain, anecdote of, 84.

PG54897.B00638
Heat, 193. Radiation and conduction of, 205. One of the chief agents in chemistry, 310. Our ignorance of the nature of, 310. Abuse of the sense of the term, 311. The general heads under which it is studied, 312. Its most obvious sources, 312. Animal heat, to what process referable, 313. Radiation and conduction of, 314. Solar heat differs from terrestrial fires, or hot bodies, 315. Principal effects of, 317. The antagonist to mutual attraction, 322. Latent heat, 322. Specific heat, 323.

PG54897.B00639
Herschel, sir William, his analysis of a solar beam, 314.

PG54897.B00640
Hipparchus, his catalogue of stars, 276.

PG54897.B00641
Holland drained of water by windmills, 61.

PG54897.B00642
Hooke almost the rival of Newton, 116.

PG54897.B00643
Huel Towan, steam-engine at, 59.
