Feb. 9, 1888] 



NATURE 



343 



In conclusion, I may say that these, circumstances do not 

 alter my conviction of fighting on the winning side. The 

 reasons of my faith I hope to give in the next journal of the 

 Royal Scottish Geographical Society. H. B. Guppy. 



17 Woodlane, Falmouth. 



Snow Crystals. 



Yesterday was very favourable for observing the beautiful 

 appearance of sunlight reflected from snow crystals. As one 

 walked across a field, stars appeared to start forth by thousands 

 from amongst the fresh-fallen snow. They were particularly 

 bright and numerous when one walked in the direction of the sun. 

 They appeared almost at all distances, and almost of all sizes, 

 those near at hand being never very large but of great brilliancy 

 and most exquisite colour. The phenomenon was sufficiently 

 striking to induce me to stop and observe it more closely, and 

 the first thing I noticed on stopping was the permanence of 

 each little star of light, although the snow was dropping melted 

 from the hedges and trees by the heat of the sun. A slight 

 movement of the head was sufficient to change the colour of a 

 red star to green or vice versa. It seemed as if the most brilliant 

 colours were seen when looking in a direction nearly but not 

 quite towards the sun. The level surface of the Snow appeared 

 as if strewn with gems — and not only near at hand, for even 

 twenty and thirty yards away a large star would shine forth 

 with a subdued but fine colour. I then noticed a peculiar uni- 

 formity of shape in these reflect'ons from snow crystals. The 

 shape never varied from that of a blunt arrow-head. This was 

 very striking in the large stars which appeared at a distance ; 

 but once noticed, it was obvious enough that even the minute 

 specks at one's feet were all of this form. Nor did the position 

 of the snow vary to any appreciable extent. The inclination 

 seemed always a little to the right, and this occurred no 

 matter in what direction I looked, whether towards the sun, 

 or away from it, or in any other direction. Wishing to know 

 the absolute size of the larger snow crystals, or combination 

 of crystals, I looked for a fine appearance, and estimated as 

 well as I could its magnitude by covering it with a small 

 object held at arm's length. The distance of the spot where 

 the crystal appeared proved to be forty-three paces from where 

 I stood, and its magnitude could not have been much less than 

 three inches in this particular case. Now if, as I suspect, the 

 form of the star which appears so persistently is due to the upper 

 or lower stem only of a complete arrangement of crystals in an 

 hexagonal shape, these combinations must occasionally be six 

 inches or more in diameter. I did not succeed in recognizing 

 any larger than very minute arrangements of crystals in the snow 

 itself, but it is obvious that the sun's rays reflected from a long 

 distance must single out those faces of crystals which happen to 

 be parallel to one another over a certain limited area. Obser- 

 vation of these reflections, therefore, calls in to our aid a power 

 of analysis in the sun's rays to detect symmetrical arrangements 

 of snow crystals quite unrecognizable by mere inspection. 

 Might I ask for some explanation of the phenomena? 



Hull, January 30. A. N. S. 



" The Mammoth and the Flood." 



Mr. Howorth's letter does little more than travel aj;ain over 

 old ground, and two only of the points raised require any notice 

 on my part ; the third — the value to be attributed to the opinion 

 of any particular geologist — being immaterial to the main ques- 

 tion. As another President of the Geological Society has said : 

 " Science needs no infallible Church, and admits of no Pope." 



In regard to the localities in which mammoth remains have 

 been found, I have not "resuscitated" any theory, but have 

 taken my facts from Mr. Howorth's book. His second letter 

 appeai-s to me to ignore a distinction which I was careful to draw 

 in my reply to his f )rmer one. That mammoth bones should be 

 found at considerable distances from, and elevations above, the 

 existing rivers, offers no difficulty. Indeed, they could not occur, 

 except accidentally, in deltas which are now in course of forma- 

 tion. But, so far as I can ascertain, there is no reason why 

 these "beds of clay and gravel" should not be deposits of 

 rivers wliich drained the same regioas under different climatal 

 conditions, in the distant ages when the mammoth lived in 

 Siberia. The case is precisely similar in England. We should 

 not expect to find mammoth bones in the mud-flats about the 

 mouths of our southern rivers, but in the old valley gravels which 



occur sometimes even 90 or 100 feet above the present level of 

 the rivers. But the facts most difficult to explain are the occur- 

 rences of the carcasses of mammoths. It was of these, and of 

 these only, that I was speaking in my letter, as I think would 

 be clear to most readers. No geologist, so far as I know, would 

 deny tliat the Siberian climate has considerably changed since 

 the mammoth wandered over its tundras, and very likely not 

 seldom got bogged ; but the question is. Has it changed sud- 

 denly or gradually ? The occurrence of the frozen carcass is 

 undoubtedly most simply explained by postulating a sudden 

 change ; but when we begin to consider what this means, the 

 remedy, though apparently so simple, seems as heroic as that of 

 the father "who cut off" his little boy's head to cure him of 

 squinting." It is then for the best preserved of these frozen 

 carcasses that I suggest the possibility of a drifting and a gradual 

 entombment by the deposits of the ancient rivers. I have again 

 consulted Mr. Howorth's book, and find, between pp. 82 and 89, 

 notices of the discovery of at least ten mammoth carcasses, mostly 

 occurring very far north in Siberia, and nearly all mentioned in 

 connection with rivers: of one it is even said, "like most of 

 the others, it is found on the bank of the river, which had been 

 undermined by floods." 



Mr. Howorth further asserts that I cannot have read his bDok 

 because I charge him with invoking a series of catastrophes 

 when he argues "in favour of one catastrophe only." But, not- 

 withstanding his disclaimer, I would like to know how we are to 

 bring about a deluge to drown the mammoth and a sudden per- 

 manent fall in temperature to freeze his carcass (query, one 

 catastrophe, or two?) without "a series of catastrophes." I 

 presume that, as this is a scientific question, we must not invoke 

 a miracle. If continents gambolled like whales — which would 

 be needed for Mr. H )worth's far-reaching flood — would this, 

 unless there were a very special arrangement of continents, so 

 materially alter the climate? and, if they did so disport them- 

 selves, what set them dancing ? If a number of insular volcanoes 

 exploded with twenty-Krakata"b force, this would be a series of 

 catastrophes, but it would probably -leave the climate unchanged. 

 If the earth's axis of rotation were suddenly altered materially 

 in position — perhaps the simplest mode of bringing about the two 

 results —would no catastrophic changes be needed to effect this 

 alteration ? Mr. Howorth's retort, in fact, indicates better than 

 anything which I can write how completely he has failed to 

 realize the conditi )ns of the problem which he attempts to 

 solve. 



But enough. It is Impossible for me to continue this corre- 

 spondence. The reviewer's task is often not a very pleasant one, 

 but a new terror would be added to the work if it involved an 

 interminable controversy with authors on matters of opinion. 

 Dreading this, I deliberately abstained from signing the review, 

 because I knew from past experience that this was my only 

 chance of escape from the flood of Mr. Howorth's controversial 

 eloquence, which, like the proverbial river, Labitttr el labetur in 

 o/nne vohibilis cevuin. YoUR Reviewer. 



An Incorrect Footnote and its Consequences. 



In following up Baltzer's erroneous reference concerning the 

 " Demonstratio eliminationis Crameriante," Mr. Muir, as de- 

 scribed in his letter on p. 246, seems at first to have been 

 singularly unlucky. For, on referring to the catalogue of Lord 

 Crawford's mathematical library under "Mollweide," although 

 the work itself was not immediately forthcoming, there was a 

 cross-reference to " Prasse, M. von," under who:e name the 

 essay was duly catalogued. The Dun Echt copies, for there are 

 two of them bound up in volumes of mathematical pamphlets, 

 are copies of the original "Demonstratio," in 8 folios, with the 

 pajes4 to 15 numbered, and the last blank. In a gap on the 

 title-page of one copy has been written " auct. Mauricius de 

 Prasse," apparently long ago, and in a German han 1. But apart 

 from this the last sentence of the first paragraph identifies the 

 author as the writer of " Usus logarithmorum," which bears 

 the same Latin form of the name in print. 



The cross-reference is due to the presence in the library of a 

 little book the title of which is worth giving in full, as it 

 contains the names between which Baltzer's mistake arose, and 

 it also gives the German form of von Prasse's name : it is 

 " Logarithmische Tafeln fiir die Zahlen, Sinus und Tangenten, 

 neu geordnet von Moritz von Prasse ehemals Prof, der Mathe- 

 matik in Leipzig, revidirt und vermehrt von Karl Brandan 

 Mollweide ordentl. Prof, der Matbematik in Leipzig, Leipzig, 



