Part 100

The greatest discovery of the age has, as already indicated, immediate and important practical bearings. The amount of thought which, even in the present day, is devoted by unscientific mechanics to the old problem of perpetual motion is far greater than is generally supposed. The principle of the conservation of energy shows that this is an impossibility; that the inventor who seeks to create force might just as well try to create matter; that the production of a perpetually moving self-sustaining machine is as far removed from human power as the bringing into existence of a new planet. In force, as in matter, the law is inexorable—_ex nihilo nihil fit_. Again, knowing the definite amount of energy obtainable from the combustion of a pound of coal, we can compare the amount we actually procure from it in our steam engines with this theoretical quantity as the limit towards which our improvements should bring us continually nearer, but which we can never exceed, or, indeed, even reach. The schemers of perpetual motion are not the only class of speculators who pursue objects which are incompatible with our principle. There are many who seek to accomplish desirable ends by inadequate means: who, for example, are aiming perhaps to accomplish the reduction of ores by a quantity of fuel less than that mechanically equivalent to the work, or who conceive that by adding to coal some substance which itself is unchanged, an indefinitely greater amount of heat may be liberated by the combustion.

Enough has been said to show that the energies of animal life can be traced to the sun as their source. The sun builds up the plant, separating oxygen from carbon. The animal—directly or mediately by devouring other animals—takes the carbonaceous matter of the plant, and reunites it with oxygen. In the plant the sun winds up the spring which gives life to the animal mechanism; for the winding-up of a spring and the separation of the atoms having chemical affinities are alike instances of supplying potential energy. In the animal there is a running-down of the potential into actual energy. It is plain also that of the total energy radiated from the sun in every direction, the earth receives but a very small part (1/2300000000). By far the larger part is diffused into space, where, for all such purposes as those with which we are concerned, it is lost. The heat which the sun sends out in a year is calculated to be equal to that which would be produced by the combustion of a layer of coal 17 miles thick over the whole surface of the luminary. Is the sun, then, a flaming fire? By no means. Combustion is not possible at its temperature; and as we know the substances which enter into its composition are the same as those we find in the earth, we know that the chemical energies of such substances could not supply the sun’s expenditure. Passing over as unsatisfactory an explanation which might occur to some minds—namely, that the sun was created hot at the beginning, and has so continued—there are two theories which attempt to account for the sun’s heat. One is that of Meyer, who supposes the heat is due to the continual impact of meteorites drawn to the sun by its gravity; and the other is that of Helmholtz, who attributes the heat to the continual condensation of the substance of the sun. Helmholtz calculates that a shrinking of the sun’s diameter by only 1/10000th of its present amount, would supply heat to last for two thousand years; while the condensation of the substance of the sun to the density of the earth would cover the sun’s expenditure for 17,000,000 of years. There is great probability that both theories may be correct, and that the cause of the sun’s heat may be considered as due in general terms to aggregation of matter, by which the original potential energy of position is converted into the actual energy of heat and light. Now, however immense may be our planetary system, the sun being continually throwing off this energy into space, there must come a time when the supplies of meteorites will fail, and when the great globe of the sun will have shrunk to its smallest dimensions. We see, then, that heat and light are produced by the aggregation of matter; the heat and light are radiated into space; the small fraction intercepted by our globe is the source of almost every movement—the original stuff, so to speak, out of which all terrestrial forces are made. The sun produces the winds, the thunderstorms, the electric currents of the Aurora, the phenomena of terrestrial magnetism, and is the source of vegetable and animal life. The waves, the rains, the mountain torrents, the flowing rivers, are the work of the sun’s emanations.

In the illustration of the energy expended on raising a weight afterwards dropped, we traced that energy into the final form of heat of a low temperature radiated into space. It would be easy to show that all energy ultimately takes the same form. Now, although it is easy to convert work into heat, there is no conceivable process by which uniformly-diffused heat can again be made to do any kind of work. The case may be compared to water, which in moving down from a higher to a lower level may be made to perform any variety of work. But when all the water has passed down from the higher level to the lower, it can no longer do any work. Whenever work is done by the agency of heat, there is always a passing from a higher temperature to a lower—a transference of heat from a hotter body to a colder. If the condenser of the steam engine had the same temperature as the steam, the machine would not work. Not only do all the energies in operation on the face of the earth continually run down into the form of radiant heat sent off by the earth into space; but our sun’s energy, and that of the suns of other systems, are also continually passing off into space; and the final effect must be a uniform diffusion of heat in a universe in which none of the varied forms of energy we now behold in operation will be possible, because all will have run down to the same dead level of uniformly-diffused heat. This startling corollary from the principle of the conservation of energy has been worked out by Sir W. Thomson under the title of “The Dissipation of Energy.” It leads us to contemplate a state of things in which all light and life will have passed away from the universe—a condition which the poet’s terrible dream of darkness, “which was not all a dream,” seems to shadow forth—

“The bright sun was extinguished, and the stars Did wander darkling in the eternal space, Rayless and pathless; and the icy earth Swung blind and blackening in the moonless air.

* * * * *

The world was void, The populous and the powerful was a lump, Seasonless, herbless, treeless, manless, lifeless— A lump of death—a chaos of hard clay. The rivers, lakes, and ocean all stood still, And nothing stirred within their silent depths.

* * * * *

The waves were dead; the tides were in their grave, The Moon, their mistress, had expired before; The winds were withered in the stagnant air, And the clouds perished; Darkness had no need Of aid from them—She was the Universe.”

The doctrine of this persistence and dissipation of energy completely harmonizes with the grand speculation termed the “nebular hypothesis,” which regards the universe as having originally consisted of uniformly diffused matter, which, being endowed with the power of gravitation, aggregated round certain centres. This process is still going on; and, according to modern speculations, light and life and motion are but manifestations of this primæval potential energy being converted into actual energy, and degrading ultimately into the form of universally-diffused heat. To quote the closing sentences of the eloquent passage in which Professor Tyndall concludes the work mentioned above, “To nature nothing can be added, from nature nothing can be taken away; the sum of her energies is constant, and the utmost man can do in the pursuit of physical truth, or in the applications of physical knowledge, is to shift the constituents of the never-varying total. The law of conservation rigidly excludes both creation and annihilation. Waves may change to ripples, and ripples to waves; magnitude may be substituted for number, and number for magnitude; asteroids may aggregate to suns, suns may resolve themselves into floræ and faunæ, and floræ and faunæ melt in air: the flux of power is eternally the same. It rolls in music through the ages, and all terrestrial energy—the manifestations of life as well as the display of phenomena—are but the modulations of its rhythm.”

The discoveries to which we have here endeavoured to attract the reader’s attention thus give rise to conceptions of the utmost grandeur and interest. We see that the sum of Nature’s energies is constant; that all the manifestations of force are but the transference of power from one position to another. And we have recognized the material source of all our terrestrial energies in the sun. Two theories have already been mentioned by which it is sought to account for the sun’s heat—the meteoric theory of Meyer and Thomson, and the shrinkage theory of Helmholtz. These both assume gravitation as the primal force from which the supply of heat and other energies must be drawn, and they assume also that the laws of radiation and of the degradation of temperature in the transformation of heat into other forces, as we find them operating at the earth’s surface, are equally in action in every region of space. Hence is deduced that conception of the final state of the universe as one of merely equally diffused temperature admitting of no further transformation. This speculation presents the _universe_ in the aspect of a clock, now indeed going, but when once run down, incapable of ever being again wound up. There seems in this view a want of symmetry, so to speak; we miss the feeling of harmonious _rhythm_ to which Tyndall refers. There is, however, another cosmic theory, well supported by accumulating facts, which assigns to gravitation a less important part in the production of solar heat and in the evolution of worlds, and it is one which supplies also a basis for the explanation of such phenomena as aerolites, comets, variable stars, the inclination of planets’ axes to their orbits, the proper motion of our sun, and that of the so called fixed stars, of all of which the nebular hypothesis fails to give any account; while, on the other hand, the _impact theory_, as it has been named, includes the other, and goes beyond it. The reader who desires to pursue this subject may be referred to Croll’s book on Stellar Evolution.

In the last few paragraphs we have been dealing with speculations as much as with discoveries. But indeed the former are the offspring of the latter, as certainly as one invention becomes the parent of others. The human mind never rests contented with the knowledge and mastery of nature actually gained, but ever seeks to pass beyond and attain still greater power. The volume we are now bringing to a close has given but brief and imperfect indications of specimens, taken here and there, of what has been done during the short period of one century. We may draw an augury for the future of man’s dominion from the powers his Promethean spirit has already grasped:

“The lightning is his slave; heaven’s utmost deep Gives up her stars, and like a flock of sheep They pass before his eye, are numbered, and roll on! The tempest is his steed, he strides the air; And the abyss shouts from her depth laid bare, “Heaven, hast thou secrets? Man unveils me; I have none.”

NOTES A AND B.

_Note A_—_Continuation of Table on page 755, showing the quantity of Coals raised annually in Great Britain._

Year. Coal raised in Tons. 1874 126,590,108 1875 133,306,458 1876 134,125,166 1877 134,179,968 1878 132,612,063 1879 133,720,393 1880 146,969,409 1881 154,184,300 1882 156,499,977 1883 163,737,327 1884 160,757,779 1885 159,351,418 1886 157,518,482 1887 162,121,576 1888 169,935,219 1889 176,916,724 1890 181,614,280 1891 185,479,126 1892 181,786,871 1893 164,325,795 1894 188,277,525

_Note B_—_CONSERVATION OF ENERGY._—_Page 804._

The statement here should have been more explicit, as it has reference to a state of things not to be realised in practice. Like the well-known “first law of motion,” it can neither be demonstrated _à priori_, nor proved by any direct and simple experiment. The first law of motion asserts that a body in motion, not acted on by any external force, will continue to move in a straight line, and with a uniform velocity. Now we cannot place a body in such a position that it will not be acted upon by some external forces; but the more we lessen the effect of external forces, the more nearly is the motion straight and uniform. Similarly in the case supposed, the intention is to show that the weight carried up is in a position to do just as much work as was done upon it. We must suppose several impracticable but conceivable conditions in order to eliminate considerations which do not concern the theoretical question; we must suppose the cord to be weightless and absolutely devoid of rigidity; the pulley to have no mass or inertia, that is to require no force to set it in motion, and to move without any friction; the air to offer no resistance; and the force of gravity to be uniform throughout the space. Some approximation to these conditions is practicable, as, for example, the pulley might be the lightest possible, and turn on friction wheels, the cord might be the finest silk thread, and so on. But it is not the influence of these external forces we are considering, but only the energy due to the position of the raised weight. Assuming, therefore, the disturbing conditions absolutely eliminated, it is not difficult to see that no downward force or pressure, however small, could be applied for ever so short a time, to the upper weight without setting the system in motion. The motion would be an accelerated one so long as the force was applied, it would become uniform when the force ceased to act; it would have a velocity proportionate to the force. In any case, after a time the descending weight would reach the ground, and for our point of view it is quite immaterial whether the time occupied by the movement were 5 minutes or 5,000 years, for be it observed, time does not enter into the definition of _work_ as it does into that of “horse-power.” Then by pushing the conceived conditions to their limits, we may see that without considering any question of conversion of motion into heat, the raised weight can, in theory at least, give back again the energy spent upon it.

INDEX

A.

Abel, Professor, 746.

Accumulators, 530.

Adhesion of locomotive, 21.

Advantages of present age, 2.

Aerolites, 30.

Air, 734.

Albert Bridge, Saltash, 283.

Alizarine, 797.

“_Alliance_” magneto-electric machine, 520.

Aluminium, 717. bronze, 719. reduced cost of, 723.

American Tract Society building, 78.

Ampère’s hypothesis, 750. rule, 492, 549.

_Amphioxus_, 679.

ANÆSTHETICS, 731.

Anemometer, 656.

Angle, limiting, or critical, 399.

Aniline, 787. black, 793. blue, 790. green, 791. purple, 788.

Anomalous magnetisation, 538.

_Anthea Cereus_, 678.

Anthracene, 796, 797.

Applegath printing machine, 312. and Cowper, ditto, 308.

Apps’s anemometer, 656. induction coil, 506.

AQUARIA, 675.

Arago, 599.

Architecture, use of iron in, 72.

Argand gas burners, 773. lamps, 595.

Armours, ships’, strengths of, 166.

Armstrong 110–ton gun, 202.

Armstrong’s guns, 192. hydraulic crane, 333.

Atoms, 733, 743.

Aurora, 504.

Australian gold, 688.

Austrian torpedoes, 229.

“_Automobile_” competition, 23.

Axolotl, 686.

B.

Bacon, Francis, 799.

Balloon, photographic, 628.

Basic process (Gilchrist’s), 66.

Battery, galvanic, 493.

Battery, secondary, 530.

Baxter House experiments, 58.

Bell Rock Lighthouse, 593.

Bells, electro-magnetic, 554.

Benzol, 783.

Bessemer, 26, 56. Channel steamer, 142. converter, 63. iron, 62. process, 64. steel, 56–67.

BIG WHEELS, 81.

Bitter Lakes, 261.

BLANCHARD LATHE, THE, 86.

Blast furnace, 40.

Blind spot in eye, 460.

Blister steel, 54.

Blood spectra, 431.

Boilers of steam engines, 13.

Boring for coals, 361.

Bourdon’s pressure gauge, 12.

Bourseul, M., 582.

Box girders, 280.

Breakwater, 258.

Breakwaters for Suez Canal, 258.

BREECH-LOADING RIFLES, 182.

Brewster, Sir D., 405, 420, 470, 474.

Bridge, projected Channel, 296.

Bridgewater Canal, 250, 266.

BRIGHTON AQUARIUM, 682.

Britannia Bridge, 280. raising tubes, 336.

British Aluminium Co., 723.

British navy in 1894, 167.

BROOKLYN BRIDGE, 303.

“Brown Bess,” 178.

Browning’s micro-spectroscopes, 434. spectroscope, 422, 432.

Brunel, 283.

Brunswick rifle, 180.

Brush dynamo, 522.

Bullet, Greener’s expanding, 182. Lebel, 188. Minié, 180.

Bullets, machinery for making, 330.

Bunsen and Kirchhoff, 422. and Roscoe, 720.

Bunsen’s battery, 496. burner, 421.

Bye-products in gas making, 772.

C.

Cable railways, 126.

Cæsium, 426.

Caissons for Forth Bridge, 293.

_Calais-Douvres_, steamship, 141.

Caledonian Canal, 250.

Calico printing machines, 321.

California, discovery of gold in, 688.

Camera, 613.

Canal, Caledonian, 250. Manchester Ship, 262. Nicaragua, 274. North Sea, 271. Panama, 272. Suez, 251.

CANTILEVER BRIDGES, 291.

“Cape Horn,” 120.

_Captain_, H.M.S., 141.

Carbon transmitter, 590.

Carbonic oxide, 44, 48.

Carbons for arc lights, 527.

Carcel lamp, 597.

Carpenter, Dr. W. B., 462.

Carriages, railway, 111. for rock drills, 358.

Carriers in pneumatic tubes, 344.

Cars, Pullman, 112.

_Castalia_, steamship, 139.

Cast-iron, composition of, 43.

Cast steel, 54.

Catoptric lighthouse apparatus, 599.

CAUSE OF LIGHT AND COLOUR, 408.

CELESTIAL CHEMISTRY AND PHYSICS, 436.

Celluloid, 622.

Central Telegraph Office, London, 574.

Centres of gravity and buoyancy, 149.

Centrifugal force, 107.

Chains, 330.

Chain-testing machine, 329.

Channel Bridge (projected), 296. steamers, 142.

CHANNEL TUNNEL, 364.

Chassepot rifle, 182.

Chemical action of light, 608. equations, 734. nomenclature, 782. symbols, 733. work of electricity, 497.

Chloroform, 608.

Chromatic aberration of eye, 462.

Chromo-lithography, 638.

Chronograph}

Chronoscope} electric, 656.

Cincinnati Suspension Bridge, 287.

_City of Rome_, steamship, 139.

Clark’s hydraulic lift graving dock, 331.

Clarke’s magneto-electric machine, 509.

Clay process, stereotyping by, 633.

Clerk Maxwell’s theory of light, 541.

“Clermont,” the, 147.

Clifton Suspension Bridge, near Bristol, 285. Niagara, 287.

COAL, 751.

Coal in Kent, 371.

COAL-GAS, 764.

COAL-TAR COLOURS, 781.

Code, telegraphic, of American War Department, 528. Morse’s, 560. Wheatstone’s dot, 565.

Cold-short iron, 62.

Colesberg, 703.

Collodion process, 618.

Colour printing, 639.

Colours not in the objects, 413. photography of, 628.

Comets, spectra of, 444.

Composition rollers, 406.

Condie’s steam-hammer, 28.

Copying principle, 86.

Cordite, 748.

Corona, 438.

Cort’s puddling furnace, 45.

Couple, mechanical, 149.

Cramp gauge, 129.

Croll, on Stellar Evolution, 810.

Crookes, 507.

Crystal Palace, an example of use of iron in architecture, 72.

Crystal Palace, 72. AQUARIUM, 677.

Crystalline lens, 455.

Cup and cone, 49.

Current, electric, 492. induced, 502. measurement of, 536.

Currents in submarine cables, 579.

D.

Daguerre, 609.

Daguerreotype, 610.

Daimler motor, 24.

Dallmeyer, 617.

Daniell’s battery, 495.

De Beers Mines, 707.

Delphi, oracle at, 739.

Dial telegraphs, 566.

Diamond cutting, 700.

Diamond, qualities of the, 698. rock drill, 359.

Diamondiferous, 703.

Diamonds, 696. use of, 701.

Dioptric lighthouse apparatus, 600.

Discoveries, progressive, 802.

Dissipation of energy, 808.

Distinct vision, 458.

D lines of sodium spectrum, 425, 441.

Dolls, talking, 674.

Domestic consumption of coal, 755, 756.

DOUBLE REFRACTION AND POLARIZATION, 399.

Dredges, Suez Canal, 255.

Drilling machine, 90.

Dry digging, 702.

Duboscq’s electric lamp, 497.

Du Moncel, 590.

DYNAMICAL ELECTRICITY, 490.

Dynamo, Siemens’, 522. Brush, 522.

E.

Earl’s Court, Great Wheel at, 83.

Earth’s circuit, 574.

Ebonite, 728.

Eccentric, 9.

Eclipse of sun, 438.

Eddystone lighthouse, 594.

Edison, 669, 670, 674.

Edison’s kinetoscope, 478.

Eiffel Tower, the, 72.

ELECTRIC LIGHTING AND ELECTRIC POWER, 519.

Electric current, 790. furnace, 722.

ELECTRIC INDUCTION, 488. launch, 534. light, cost of, 43.

Electric light in lighthouses, 515. telegraph, 598. torpedo, 547. tramway, 532. welding, 537.

ELECTRICITY, 481.

ELECTRICITY, THE NEW, 538.

Electrode, 497.

Electro-magnet, 500.

Electromotive force, 494.

Electro-plating, 499, 518.

Electrotyping, 634.

Elementary bodies, 716.

ELEMENTARY PHENOMENA OF MAGNETISM AND ELECTRICITY, 483.

Elswick 4·7–in. gun, 206. guns, 194.

Energy, 806.

Ether, 735. the luminiferous, 408.

Exhaustion of coal, 755, 756, 757.

Expansive working of steam, 8, 17.

Explosion by concussion, 745. of locomotive, 21. of torpedoes, 229.

EXPLOSIVES, 225, 740. different effects of, 748. names and classes of, 750.

EYE, THE, 451. dimensions of some parts of, 462.

Eye not optically perfect, 462.

Eyeballs, muscles of, 461.

F.

Fairbairn, Sir W., 280.

Faraday, 506, 508, 735. ventilating gas-burner, 773.

Faure’s accumulator, 530.

Fellahs, 255.

Ferris wheel, Chicago, 81.

Field telegraphs, 555.

FIRE-ARMS, 169.

Fish-plates, 105.

Fizeau, 386.

Floating matter in air, 383.

Fluids, electric, 487.

Fly-wheels, 7.

Force, conservation of, 804. electromotive, 494.

FORTH BRIDGE, THE, 311.

Foucault, 387.

Fovea centralis, 456, 457.

Fraser-Woolwich guns, 195.

Fraunhofer’s lines, 420, 436.

Fresnel’s mirrors, 409. measurement of velocity of light, 600.

Fribourg Suspension Bridge, 286.

Froment’s dial telegraph, 567.

Furnace, electric, 322.

G.

Galvanic batteries, 493, 494.

Galvanometer, 493. mirror, 570.

Gas engine, 25. governor, 769. holder, 766. making apparatus, 765. meters, 775. pressure, 769. retorts, 766.

Gases of blast furnace, 49.

Gatling battery gun, or mitrailleur, 219.

Gauge, broad and narrow, 106. Bourdon’s pressure, 12.

Geissler’s tubes, 505.

Ghost, Pepper’s, 392.

Giffard’s injector, 11.

GIRDER BRIDGES, 280.

Glass, strains in, 407.

_Glatton_, H. M. S., 161.

Glynde, electric railway, 534.

GOLD, 686.

GOLD AND DIAMONDS, 687.

Gold-mining operations, 690.

Goodyear, Mr., 727.

Governor of steam engines, 6.

Gower Street Station, 114.

Gramme magneto-electric machine, the, 511.

Graphophone, 672.

Graphotype, 644.

Gray, 590.

GREAT BROOKLYN BRIDGE, 303.

_Great Eastern_, 133, 152, 330, 465, 578.

GREATEST DISCOVERY OF THE AGE, 801.

Greener’s expanding bullet, 182.

Grove, Sir W. R., 804.