FOOTNOTES:
[1] Other green lines have since been discovered in the auroral spectrum; and occasionally a red line is seen.
[2] In the Quarterly Journal of Science for October 1866, a more detailed but somewhat less popular account of the subject of the above paper is presented. A few months earlier, a skilfully-written paper on the same subject, from the pen of Mr. J. M. Wilson, of Rugby, had appeared in the Eagle, a magazine written by and for
members of St. John’s College, Cambridge. Although my paper in
the Quarterly Journal of Science was written quite independently of Mr. Wilson’s (which, however, I had read), yet it chanced that in describing the same mathematical relations, and the same sequence of events, I here and there used language closely resembling his. I fear this led for a while to some misconception; but I was fortunately able to show in Mr. De la Rue’s address to the Astronomical Society, on the same subject, passages yet more strikingly resembling some in Mr. Wilson’s paper (written subsequently and quite independently). The fact would seem to be that if two persons describe exactly the same events, and deal with exactly the same mathematical relations, it is almost certain that in more than one passage they will use somewhat similar expressions.
I was actually indebted to Mr. Wilson’s paper for one illustration, however,—that derived from the movements of a supposed artificial moon; and I think that had his paper appeared in a magazine printed for general circulation, I should have referred to it. As it was, this seemed useless so far as the readers of the Quarterly Journal of Science were concerned. The circumstances of the case were, indeed, far from calling for a reference; while I had in a sense made the illustration my own by detecting an important miscalculation in the original (the amount of advance being either doubled or halved—I forget which). Had I referred to Mr. Wilson’s paper, I must needs have mentioned this mistake; and it would have appeared as though I had had no other purpose in making the reference.
I mention these matters to explain what I fear my esteemed fellow-collegian was disposed at the time to regard as either a wrong or a slight. Nothing was further from my intention than either.
[3] The reader will remember the time at which the essay appeared. For several reasons it seems well to leave the essay unaltered. In the second series of Light Science a later stage is presented, and the account is carried up to the present date in my work on The Transits of Venus.
[4] It is held to be of the utmost importance that all the observing parties should use similar telescopes.
[5] So far back as 1789, John Williams, in his Natural History of the Mineral Kingdom, discussed the question of the ‘Limited Quantity of Coal in Great Britain.’ The following extracts are taken from an excellent paper on the exhaustion of our coal in the Popular Science Review for July 1866, by Mr. Lemoran, Colliery Viewer. ‘I have no doubt,’ says Williams, ‘that the generality of the inhabitants of Great Britain believe that our coal mines are inexhaustible; and the general conduct of the nation, so far as relates to this subject, seems to imply that this is held as an established fact. If it was not a generally received opinion, would the rage for exporting coals be allowed to go on without limitation or remorse? But it is full time that the public were undeceived in a matter which so nearly concerns the welfare of this flourishing island.... When our coal mines are exhausted, the prosperity and glory of this flourishing and fortunate island are at an end. Our cities and great towns must then become ruinous heaps for want of fuel, and our mines and manufactories must fail from the same cause, and then, consequently, our commerce must vanish. In short, the commerce, wealth, importance, glory, and happiness of Great Britain will decay and gradually dwindle away to nothing, in proportion as our coal and other mines fail.’ Mr. Williams also solves in a very summary manner the problem of England’s fate after her coal stores shall be exhausted. ‘The future inhabitants of this island must live,’ says he, ‘like its first inhabitants, by fishing and hunting.’
[6] In 1854, the yield was 64,661,401 tons; in 1864, the yield was 92,787,873: the average increase per annum was, therefore, no less than 2,812,647 tons.
[7] I have obtained a somewhat different result from a computation I have just gone through. I make the consumption 291 millions in 1900, and 1,446 millions in 1950. Mr. Lemoran seems to have taken the percentage at 3½ instead of 3¼. It is worth noticing how seriously a small change in the percentage affects the result; the consumption in 1950 becoming 1,760 millions of tons, instead of 1,446 millions.
[8] The year 1863 was the last whose statistics were available for Mr. Jevons’s purpose; and estimating from either 1860 or 1862 would give a result smaller than either of the above. Indeed, the consumption was less in 1862 than in 1861.
[9] See ‘Light Science’ (second series) for a discussion of later researches.
[10] The wave did little mischief, the winds being easterly.
[11] This opinion Dr. Carpenter has since somewhat modified. It will be remembered, of course, that the evidence derived from the nature of superposed strata is in no way affected by what is shown above to hold with adjacent deposits.
[12] I remember to have read that in this hurricane guns which had long lain under water were washed up like mere drift upon the beach. Perhaps this circumstance grew gradually into the incredible story above recorded.
[13] A ship by scudding before the gale may—if the captain is not familiar with the laws of cyclones—go round and round without escaping. The ship ‘Charles Heddle’ did this in the East Indies, going round no less than five times.
[14] The reader need hardly be reminded of the complete fulfilment of this anticipation, during the war between France and Germany.
[15] The grip is never properly caught without the pause; but anything beyond a momentary pause is a bad fault in style.
[16] I write this with full knowledge that many Oxford men deny the fact. I have rowed behind Cambridge, Oxford, and London strokes, and have several times taken the place (number 2 thwart) of a London waterman in a four (‘stroked’ by John Mackinney) training for the Thames Regatta. So that I have had ample opportunities for comparing different rowing styles; and I am satisfied that the main defect of the real Cambridge style was (and perhaps is) an exaggeration of the sound rule that a boat should be propelled rather by the body than by the arms. The very swing in a Cambridge boat shows that this must be so. On the other hand, the Thames watermen do too much arm-work; and hence seem to double a little over their oars. I once rowed with some Cambridge friends from London nearly to Oxford and back, taking a Thames waterman as ‘help.’ We set him, at first, for our strokesman, but we soon had to make him row bow, for we could none of us stand his gripping, arm-working style.
[17] The race (that of 1869) was one of the best ever rowed, and the time of the winners (Oxford) better than in any former race.
[18] This article was written early in March 1868.
[19] Another well-known instance, where ‘Patroclus, sent in hot haste for news by a man of the most fiery impatience, is button-held by Nestor, and though he has no time to sit down, yet is obliged to endure a speech of 152 lines,’ is accounted for by Gladstone in a different manner.
[20] Besides Homer’s reference, both in the ‘Iliad’ and ‘Odyssey,’ to poetic recitations at festivals, there is the well-known invocation in Book II. To what purpose would the mere writer of poetry pray for an increase of his physical powers? Nothing could be more proper, says Gladstone, if Homer were about to recite; nothing less proper if he were engaged on a written poem.
[21] We may exclude Delphinus as probably later than Homer’s time, though mentioned by Aratus.
[22] Compare the description of the constellation Draco by Aratus:—
Swol’n is his neck—eyes charg’d with sparkling fire
His crested head illume. As if in ire
To Helice he turns his foaming jaw
And darts his tongue, barb’d with a blazing star.
—Lamb’s Translation.
[23] It is scarcely necessary to remark that, no importance is to be attached to the numerical relations in this and other passages. In the original work describing a zodiac-dome, the exact number of constellations representing fishes, dogs, or the like, would of course be mentioned; but any changes necessary to Homer’s purpose in describing a shield would unhesitatingly have been introduced by him subsequently. It is singular, however, that we should have here, and in the passage quoted farther on as referring to Orion and the Dogs, the number two specially mentioned. The latter instance is the more remarkable inasmuch as the mention of men and hares would lead one to expect that more than two dogs would be introduced. I would suggest as a sufficient reason for this peculiarity that the verbal alterations necessary to pluralise some of the objects in the dome would be more easily effected than those necessary to undualise others.