178 



NATURE 



[Dec, 22, 1887 



St. Moritz lies on the northern slope of a valley running fro:n 

 south-west to north-east. At the beginning of the observations 

 the opposite slope was buried in snow, but the northern slope 

 both above and below the point of observation was almost free 

 from snow. Thus the most brightly illuminated part of the 

 ground surface was of a dull brown or gray colour. Under 

 these circumstances, the reading was about 50° in the middle of 

 the day, being a little higher earlier and later, viz. about 52° 

 at 10 a.m. (date October 21 and 22). These readings, as well as 

 those mentioned below, refer to the highest point of the sky, 

 which is distant 90° from the sun, and were taken when the 

 whole sky was free from cloud. On October 26, after a five-inch 

 fall of snow, the reading was 41° at 10.15 ^•"^• 



By October 29 most of the fresh snow had gone, and I found 

 at 11.40 a.m. the reading as high as 48°. After this we had 

 several feet of, snow, and at 12.50 p.m. on November 13, the 

 reading was again 41°. Each of these readings is the mean of 

 four, and I find two readings of the same thing seldom differ 

 more than 2°. Hitherto I have not been able properly to evaluate 

 the readings of my instrument in absolute measure, though I hope 

 to do so later. But to gain an approximate idea of their meaning, 

 I have calculated the polarizing power of the two piles on the 

 assumptions — first that Fresnel's laws of the reflection of polarized 

 light are accurate, and secondly that the index of refraction of my 

 plates is i '52. We may consider the light from the sky as con- 

 sisting of two parts completely polarized, one in the plane of the 

 sun, and the other perpendicular thereto. The ratio of these 

 parts is '376 for the reading 40°, and "271 for the reading 50°. 

 Again we may divide the light into a part unpolarized and a 

 part completely polarized in the plane of the sun. The ratio of 

 these parts is '546 for 40° and '428 for 50°. So it seems fair to 

 conclude that the light reflected from the fresh snow was sufficient 

 to increase the unpolarized part of the sky light by more than a 

 quarter. James C. McConnel. 



St. Moritz, Switzerland, December 10. 



The Ffynnon Beuno and Cae Gwyn Caves. 



I WILL answer Dr. Hicks's question in as few words as pos- 

 sible. Nothing is to be gained by terming me a "highly 

 prejudiced" observer, or by saying my views are of "no con- 

 sequence " and " not worth anything." Your readers can form 

 their own conclusions on these points. I am not "highly 

 prejudiced" against, neither have I any "bias against," the 

 existence of pre-Glacial man or of his "migrations"; on the 

 contrary, I favour these subjects. 



I did see the section of drift exposed at the Cae Gwyn Cave, 

 and I can hardly describe it (from my own point of view) with- 

 out giving offence. My view is this : the section showed 

 nothing but rain-wash derived from the closely- adjoining non- 

 Glacial drift. The section showed a re- made deposit, hori- 

 zontally stratified, and with stones resting on their flat sides. 

 No doubt there were Glacial stones in the rain-wash, derived 

 from the ever-shifting post-Glacial marine drift close by ; the 

 latter being merely a re-laid Glacial drift. Stones with Glacial 

 scratches may be found in the lower gravels of the Thames. 



To me, the caves and their surroundings are in the highest 

 degree suspicious, and in size insignificant, and not comparable 

 with large and typical caves. They are small and painfully 

 narrow tortuous passages only, on a hill-side, and close to the 

 surface. The lower cave is furnished with a very large hole, 

 opening up to the surface just above ; and the upper cave had 

 at one time a similar opening. The post-Glacial drift above is 

 always on the move, and every shower of rain brings it down 

 with its derived stones. 



Since writing to Nature, in November 3, I have referred to 

 some of the papers published on these caves. I turned first to 

 the list of mammalian remains, only however to find that the 

 animals (like the implements) are entirely chai-acteristic of the 

 most recent post-Glacial deposits. Even near London we get 

 in gravels of no great comparative antiquity the bones oiElephas 

 antiqtius, but in the caves merely E. pritnigcnius is found. As 

 regards antiquity, the animals no doubt overlap at both ends of 

 the scale, but their meaning, as found in these caves, points in 

 one direction only, and that is to the most recent and not to the 

 most remote of Palaeolithic times. None of the cave mammals 

 are characteristic of pre-Glacial deposits. 



It would seem that Dr. Hicks does not realize the nature of 

 Dr. John Evans's criticism. La Madelaine is the newest of caves, 

 and represents the most recent of Palaeolithic times : it is 



a kind of connecting link between Palseolithic and Neolithic 

 times. Therefore, if Dr. Evans's criticism is taken with mine, 

 the two clearly prove that there is a distinct chronological value 

 in the classification, not that there is "no chronological value" 

 as concluded by Dr. Hicks. Dr. Hicks also appears not to 

 realize the fact that river-drift and cave implements do not only 

 differ in roughness and abrasion but in style. The cave men 

 used different implements from the river-drift men, they were 

 changing from savagery to barbarism. If Dr. Hicks produces 

 implements made by pre-Glacial men, he must show us some- 

 thing obviously older than the oldest river-drift tools, not fall 

 back upon refined tools which are, to re-quote Dr. Evans, " pre- 

 cisely like many from the French caves of the reindeer period, 

 such for instance as La Madelaine." If Dr. Hicks abandons 

 his scraper, he is still in no better position, for his finely re- 

 trimmed knife and the implement in the British Museum are 

 identical in age and character with it. So are the flakes : the 

 one with long narrow facets is characteristic of the latest, not of 

 the earliest work. So is the pointed and drilled bone. No 

 drilled bones have been found in moderately old river-gravels, 

 and what is more, no instrument suitable for boring a small hole 

 through bone has ever been found in such a gravel. Drilled 

 bones and small flint drills belong to the very latest of Palaeo- 

 lithic times. In the remains of my own collection of 

 Palaeolithic implements I have here over a thousand examples 

 of the major clas«, and an equal number of minor forms illustra- 

 tive of the development of knife and scraper forms, but they 

 give no support whatever to Dr. Hicks's conclusions ; they all, in 

 fact, point in a diametrically different direction. I am acquainted 

 with Prof. Prestwich's views, and I believe I was the first 

 person to find implements in the highest terraces of the Thames 

 Valley ; but I do not see that Prof. Prestwich's conclusions have 

 any direct bearing on the Ffynnon Beuno and Cae Gwyn caves. 



I do not suppose that any opinion of mine will influence Dr. 

 Hicks, and I have no wish to influence him or any other 

 observer. I merely wish to put on record the fact that, after 

 many years' experience amongst drifts, and implements, and 

 fossil bones, my conclusions are entirely opposed to Dr. Hicks's. 



Dunstable. Worthington G. Smith. 



P. S. — Since the above has been in type, I have seen the 

 report in last week's Nature (p. 166), but I prefer to let my 

 letter stand just as written before the report was seen by me. 

 Prof. Hughes has cut away the geological and palaeontologicai 

 supports ; I shall be content to resist the idea of the pre Glacial 

 age of these caves on purely archaeological grounds. — W. G. S. 



The Planet Mercury. 



The planet observed on the mornings of December 7 and 9 

 by your correspondent " G. F. P." (Nature, December 15, 

 p. 151), was probably not Mercury but Jupiter, as these bodies 

 were near together at the time, and the latter was by far the 

 brightest and mo.-t conspicuous. The circumstances, described 

 by "G. F. P.," under which the object was noticed render it 

 certain that it could not have been Mercuiy, for the latter was 

 decidedly small, and might have been easily overlooked on the 

 several mornings I saw it early in the present month. Jupiter, 

 on the other hand, was very bright and plain, and might easily 

 attract attention in the way stated by your correspondent. On 

 the 9th instant the two planets were about 3° apart, Jupiter 

 being situated to the west of Mercury. 



Had " G. F. P." really observed the latter planet, he would 

 have instantly remarked its half-moon phase in his 35-inch tele- 

 scope, and must have mentioned Jupiter, as well as Venus, as 

 visible at the same time. 



There is no difficulty in observing Mercury with the naked 

 eye if the planet is carefully looked for in the proper spot, at 

 the times of his eastern elongations in the first half of the year 

 and at the western elongations in the last half. I have seen the 

 planet on certainly more than fifty occasions. In May 1876 I 

 noticed Mercury on thirteen different evenings. Sometimes the 

 planet is quite conspicuous in the twilight as a naked-eye 

 object. W. F. Denning. 



Bristol, December 16. 



Meteor of November 15. 



In Nature of December i (p. 105) Mr. B. Tniscott writes 

 of a wonderfully fine meteor seen at Falmouth on the night of 

 Tuesday, the 15th ult , and asks in effect if it was seen by other 



