Part 36

[10] It may be briefly sketched, perhaps, in a note. The force necessary to draw the earth inwards in such sort as to make her follow her actual course is proportional to (i) the square of her velocity directly, and (ii) her distance from the sun inversely. If we increase our estimate of the earth’s distance from the sun, we, in the same degree, increase our estimate of her orbital velocity. The square of this velocity then increases as the square of the estimated distance; and therefore, the estimated force sunwards is increased as the square of the distance on account of (i), and diminished as the distance on account of (ii), and is, therefore, on the whole, increased as the distance. That is, we now regard the sun’s action as greater at this greater distance, and in the same degree that the distance is greater; whereas, if it had been what we before supposed it, it would be less at the greater distance as the square of the distance (attraction varying inversely as the square of the distance). Being greater as the distance, instead of less as the square of the distance, it follows that our estimate of the sun’s absolute force is now greater as the cube of the distance. Similarly, if we had diminished our estimate of the sun’s distance, we should have diminished our estimate of his absolute power (or mass) as the cube of the distance. But our estimate of the sun’s volume is also proportional to the cube of his estimated distance. Hence our estimate of his mass varies as our estimate of his volume; or, our estimate of his mean density is constant.

[11] Only very recently an asteroid, Hilda (153rd in order of detection), has been discovered which travels very much nearer to the path of Jupiter than to that of Mars—a solitary instance in that respect. Its distance (the earth’s distance being represented by unity), is 3·95, Jupiter’s being 5·20, and Mars’s 1·52; its period falls short of 8 years by only two months, the average period of the asteroidal family being only about 4½ years. Five others, Cybele, Freia, Sylvia, Camilla, and Hermione, travel rather nearer to Jupiter than to Mars; but the remaining 166 travel nearer to Mars, and most of them much nearer.

[12] Even this statement is not mathematically exact. If the rails are straight and parallel, the ratio of approach and recession of an engine on one line, towards or from an engine on the other, is never quite equal to the engines’ velocities added together; but the difference amounts practically to nothing, except when the engines are near each other.

[13] I have omitted all reference to details; but in reality the double battery was automatic, the motion of the observing telescope, as different colours of the spectrum were brought into view, setting all the prisms of the double battery into that precise position which causes them to show best each particular part of the spectrum thus brought into view. It is rather singular that the first view I ever had of the solar prominences, was obtained (at Dr. Huggins’s observatory) with this instrument of my own invention, which also was the first powerful spectroscope I had ever used or even seen.

[14] It varies more in some months than in others, as the moon’s orbit changes in shape under the various perturbing influences to which she is subject.

[15] It may seem strange to say that one hundred and twenty years after the passage of a comet which last passed in 1862, and was then first discovered, August meteors have been seen. But in reality, as we know the period of that comet to be about one hundred and thirty years, we know that the displays of the years 1840, 1841, etc., to 1850, must have followed the preceding passage by about that interval of time.

[16] The D line, properly speaking, as originally named by Fraunhofer, belongs to sodium. The line spoken of above as the sierra D line is one close by the sodium line, and mistaken for it when first seen in the spectrum of the coloured prominences as a bright line. It does not appear as a dark line in the solar spectrum.

[17] Since this was written, I have learned that Mr. Backhouse, of Sunderland, announced similar results to those obtained at Dunecht, as seen a fortnight or so earlier.

[18] Here no account is taken of the motions of the stars within the system; such motions must ordinarily be minute compared with the common motion of the system.

[19] Eight pictures of nebulæ were exhibited in illustration of this peculiarity.

[20] Sir John Herschel long since pointed to the variation of our sun as a possible cause of such changes of terrestrial climate.

[21] During these journeys the Atlantic was sounded, and Scoresby’s estimate of the enormous depth of the Atlantic to the north-west of Spitzbergen was fully confirmed, the line indicating a depth of more than two miles. It was found also that Spitzbergen is connected with Norway by a submarine bank.

[22] It is far from improbable that a change has taken place in the climate of the part of the Arctic regions traversed by Koldewey; for the Dutch seem readily to have found their way much further north two centuries ago. Indeed, among Captain Koldewey’s results is one which seems to indicate the occurrence of such a change. The country he explored was found to have been inhabited. “Numerous huts of Esquimaux were seen, and various instruments and utensils of primitive form; but for some reason or other the region seems to have been finally deserted. The Polar bear reigns supreme on the glaciers, as the walrus does among the icebergs.” Not improbably the former inhabitants were forced to leave this region by the gradually increasing cold.

[23] Dr. Emile Bessels was tried at New York in 1872, on the charge of having poisoned Captain Hall, but was acquitted.

[24] The phenomena here described are well worth observing on their own account, as affording a very instructive and at the same time very beautiful illustration of wave motions. They can be well seen at many of our watering-places. The same laws of wave motion can be readily illustrated also by throwing two stones into a large smooth pool, at points a few yards apart. The crossing of the two sets of circular waves produces a wave-net, the meshes of which vary in shape according to their position.

[25] It is a pity that men of science so often forget, when addressing those who are not men of science, or who study other departments than theirs, that technical terms are out of place. Most people, I take it are more familiar, on the whole, with eyelids than with _palpebræ_.

[26] This nautical expression is new to me. Top-gallants—fore, main, and mizen—I know, and forecastle I know, but the top-gallant forecastle I do not know.

[27] The instrument was lent to Mr. Huggins by Mr. W. Spottiswoode. It has been recently employed successfully at Greenwich.

[28] Thus in _Christie Johnstone_, written in 1853, when Flucker Johnstone tells Christie the story of the widow’s sorrows, giving it word for word, and even throwing in what dramatists call “the business,” he says, “‘Here ye’ll play your hand like a geraffe.’ ‘Geraffe?’ she says; ‘that’s a beast, I’m thinking.’ ‘Na; it’s the thing on the hill that makes signals.’ ‘Telegraph, ye fulish goloshen!’ ‘Oo, ay, telegraph! geraffe’s sunnest said for a’.’” “Playing the hand like a telegraph” would now be as unmeaning as Flucker Johnstone’s original description.

[29] Not “to represent the gutta-percha,” as stated in the _Times_ account of Mr. Muirhead’s invention. The gutta-percha corresponds to the insulating material of the artificial circuit; viz., the prepared paper through which the current along the tinfoil strips acts inductively on the coating of tinfoil.

[30] I must caution the reader against Fig. 348 in Guillemin’s _Application of the Physical Forces_, in which the part _c d_ of the wire is not shown. The two coils are in reality part of a single coil, divided into two to permit of the bar being bent; and to remove the part _c d_ is to divide the wire, and, of course, break the current. It will be seen that _c d_ passes from the remote side of coil _b c_, Fig. 6, to the near side of coil _d e_. If it were taken round the remote side of the latter coil, the current along this would neutralize the effect of the current along the other.

[31] The paper is soaked in dilute ferrocyanide of potassium, and the passage of the current forms a Prussian blue.

[32] Sir W. Thomson states, in his altogether excellent article on the electric telegraph, in Nichol’s _Cyclopædia_, that the invention of this process is due to Mr. Bakewell.

[33] It is to be noticed, however, that the recording pointer must always mark its lines in the same direction, so that, unless a message is being transmitted at the same time that one is being received (in which case the oscillations both ways are utilized), the instrument works only during one-half of each complete double oscillation.

[34] It seems to me a pity that in the English edition of this work the usual measures have not been substituted throughout. The book is not intended or indeed suitable for scientific readers, who alone are accustomed to the metric system. Other readers do not care to have a little sum in reduction to go through at each numerical statement.

[35] Hanno’s _Periplus_—the voyage of Hanno, chief of the Carthaginians, round the parts of Libya, beyond the Pillars of Hercules, the narrative of which he posted up in the Temple of Kronos.

[36] I may mention one which occurred within my own experience. A mastiff of mine, some years ago, was eating from a plate full of broken meat. It was his custom to bury the large pieces when there was more than he could get through. While he was burying a large piece, a cat ran off with a small fragment. The moment he returned to the plate he missed this, and, seeing no one else near the plate, he, in his own way, accused a little daughter of mine (some two or three years old) of the theft. Looking fiercely at her, he growled his suspicions, and would not suffer her to escape from the corner where his plate stood until I dragged him away by his chain. Nor did he for some time forget the wrong which he supposed she had done him, but always growled when she came near his house.

[37] It may be suggested, in passing, that the association which has been commonly noticed between prominent eyeballs and command of language (phrenologists place the organ of language, in their unscientific phraseology, behind the eyeballs) may be related in some degree to the circumstance that in gradually emerging from the condition of an arboreal creature the anthropoid ape would not only cease to derive advantage from sunken eyes, but would be benefited by the possession of more prominent eyeballs. The increasing prominence of the eyeballs would thus be a change directly associated with the gradual advance of the animal to a condition in which, associating into larger and larger companies and becoming more and more dependent on mutual assistance and discipline, they would require the use of a gradually extending series of vocal signs to indicate their wants and wishes to each other.

[38] The word hypothesis is too often used as though it were synonymous with theory, so that Newton’s famous saying, “Hypotheses non fingo” has come to be regarded by many as though it expressed an objection on Newton’s part against the formation of theories. This would have been strange indeed in the author of the noblest theory yet propounded by man in matters scientific. Newton indicates his meaning plainly enough, in the very paragraph in which the above expression occurs, defining an hypothesis as an opinion not based on phenomena.

[39] I find it somewhat difficult to understand clearly Mr. Mivart’s own position with reference to the general theory of evolution. He certainly is an evolutionist, and as certainly he considers natural selection combined with the tendency to variation (as ordinarily understood) insufficient to account for the existence of the various forms of animal and vegetable existence. He supplies the missing factor in “an innate law imposed on nature, by which new and definite species, under definite conditions, emerged from a latent and potential being into actual and manifest existence;” and, so far as can be judged, he considers that the origin of man himself is an instance of the operation of this law.

[40] The Middle Tertiary period—the Tertiary, which includes the Eocene, Miocene, and Pliocene periods, being the latest of the three great periods recognized by geologists as preceding the present era, which includes the entire history of man as at present known geologically.

[41] Closely following in this respect his illustrious namesake Roger, who writes, in the sixth chapter of his _Opus Majus_, “_Sine experientia nihil sufficienter sciri potest._”

[42] Fibrine and albumen are identical in composition. _Caseine_, which is the coagulable portion of milk, is composed in the same manner. The chief distinction between the three substances consists in their mode of coagulation; fibrine coagulating spontaneously, albumen under the action of heat, and caseine by the action of acetic acid.

[43] To this article of the Professor’s faith decided objection must be taken, however.

[44] Those whose custom it is to regard all theorizing respecting the circumstances revealed by observation as unscientific, may read with profit an extremely speculative passage in Newton’s _Principia_ relating to the probable drying up of the earth in future ages. “As the seas,” he says, “are absolutely necessary to the constitution of our earth, that from them the sun, by its heat, may exhale a sufficient quantity of vapours, which, being gathered together into clouds, may drop down in rain, for watering of the earth, and for the production and nourishment of vegetables; or being condensed with cold on the tops of mountains (as some philosophers with reason judge), may run down in springs and rivers; so for the conservation of the seas and fluids of the planets, comets seem to be required, that, from their exhalations and vapours condensed, the wastes of the planetary fluids spent upon vegetation and putrefaction, and converted into dry earth, may be ultimately supplied and made up; for all vegetables entirely derive their growths from fluids, and afterwards, in great measure, are turned into dry earth by putrefaction; and a sort of slime is always found to settle at the bottom of putrefied fluids; and hence it is that the bulk of the solid earth is continually increased; and the fluids, if they are not supplied from without, must be in a continual decrease, and quite fail at last. I suspect, moreover, that it is chiefly from the comets that spirit comes which is indeed the smallest but the most subtle and useful part of our air, and so much required to sustain the life of all things with us.”

[45] See my “Science Byways,” pp. 244, 245.

[46] The following passage from Admiral Smyth’s Bedford Catalogue is worth noticing in this connection:—“We find that both the Chinese and the Japanese had a zodiac consisting of animals, as _zodiacs_ needs must, among which they placed a tiger, a peacock, a cat, an alligator, a duck, an ape, a hog, a rat, and what not. Animals also formed the _Via Solis_ of the Kirghis, the Mongols, the Persians, the Mantshus, and the ancient Turks; and the Spanish monks in the army of Cortes found that the Mexicans had a zodiac with strange creatures in the departments. Such a striking similitude is assuredly indicative of a common origin, since the coincidences are too exact in most instances to be the effect of chance; but where this origin is to be fixed has been the subject of interminable discussions, and learning, ignorance, sagacity, and prejudice have long been in battle array against each other. Diodorus Siculus considers it to be Babylonian, but Bishop Warburton, somewhat dogmatically tells us, ‘Brute worship gave rise to the Egyptian asterisms prior to the time of Moses.’” There is now, of course, very little reason for questioning that Egyptian astronomy was borrowed from Babylon.

Transcriber’s Notes

Cover created by Transcriber and placed in the Public Domain.

Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed.

Simple typographical errors were corrected; occasional unbalanced quotation marks retained.

Ambiguous hyphens at the ends of lines were retained.

Some ditto marks have been replaced by the actual text.

Page 83: In the illustration, “O” should be “C”.

Page 171: There is no obvious closing quotation mark to match the opening mark at “of most unusual age and thickness”.

Page 192: “Divided even between the ocean” may be a misprint for “evenly”.

Page 197: No matching closing quotation mark for the opening mark at “the small bright spot”.

Page 222: Transcriber added an opening quotation mark at “Down his back” to match the closing mark after “He was seen by every one on board.”

Page 230: No matching closing quotation mark for the opening mark at “a whale of large size”.

Page 302: Transcriber added an opening quotation mark at “About fifty years ago” to match the closing mark after “fed himself with the other.”

Page 372: No matching opening quotation mark for the closing mark after “its lower extremity.”

Page 385: No matching closing quotation mark for the opening mark at “sweeps off from”.

End of Project Gutenberg's Pleasant Ways in Science, by Richard A. Proctor