43^ 



NATURE 



[December 19, 1912 



quent rinsing and wiping. Practically the easiest 

 \va\' to bring a plate back to its original condition 

 is to rub it with soapy water. But even this does 

 not fully succeed with the test-tube, probably on 

 account of the less effective rubbing and wiping 

 near the closed end. But what exactly is involved 

 in rubbing and wiping? I ventured to suggest 

 before that possibly grease may penetrate the glass 

 somewhat. From such a situation it might not 

 easily be removed, or, on the other hand, intro- 

 duced. 



There is another form of experiment from which 

 I had hoped to reap decisive results. The interior 

 of a mass of glass cannot be supposed to be 

 greasy, so that a surface freshly obtained by frac- 

 ture should be clean, and give the dark deposit. 

 One difficulty is that the character of the deposit 

 on the irregular surface is not so easily judged. 

 I\[y first trial on a piece of plate glass § in. thick, 

 laroken into two pieces with a hammer, gave 

 anomalous results. On part of each new surface 

 the breath was deposited in thin lamina? capable 

 of showing colours, but on another part the water 

 masses were decidedly smaller, and the deposit 

 could scarcely be classified as black. The black 

 and less black parts of the two surfaces were 

 those which had been contiguous before fracture. 

 That there should be a well-marked difference in 

 this respect between parts both inside a rather 

 small piece of glass is very surprising. I have 

 not again met with this anomaly ; but further 

 trials on thick glass have revealed deposits which 

 may be considered dark, though I was not always 

 satisfied that they were so dark as those obtained 

 on flat surfaces with the blow-pipe or hot sulphuric 

 acid. Similar experiments with similar results 

 may be made upon the edges of ordinary glass 

 plates (such as are used in photography), cut with 

 a diamond. The breath deposit is best held pretty 

 close to a candle-flame, and is examined with a 

 magnifier. 



In conclusion, I may refer lo two other related 

 matters in which my experience differs from that 

 of INIr. Aitken. He mentions that with an alcohol 

 flame he "could only succeed in getting very slight 

 indications of any action." I do not at all under- 

 stand this, as I have nearly always used an alcohol 

 flame (with a mouth blow-pipe) and got black de- 

 posits. Thinking that perhaps the alcohol which 

 I generally use was contaminated, I replaced it 

 by pure alcohol, but without any perceptible 

 difference in the results. 



Again, I had instanced the visibility of a gas 

 flame through a dewed plate as proving that part 

 of the surface was uncovered. I have improved 

 the experiment by using a curved tube through 

 which to blow upon a glass plate already in posi- 

 tion between the flame and the eye. I have not 

 been able to find that the flame becomes invisible 

 (with a well-defined outline) at any stage of the 

 deposition of dew. Mr. Aitken mentions results 

 pointing in the opposite direction. Doubtless, the 

 highly localised light of the flame is favourable. 



Rayleigh. 

 NO. 2251, VOL. 90] 



PALEOLITHIC MAN. 



THE fossil human skull and mandible to be 

 described by Mr. Charles Dawson and Dr. 

 Smith Woodward at the Geological Society as we 

 go to press is the most important discovery of its 

 kind hitherto made in England. The specimen 

 was found in circumstances which seem to leave 

 no doubt as to its geological age, and the charac- 

 ters it shows are themselves sufficient to denote 

 its extreme antiquity. It was met with in a gravel 

 which was deposited by the river Ouse near 

 Piltdown Common, Fletching, Sussex, at a time 

 when that river flowed at a level eighty feet above 

 its present course. 



Although the basin of the stream is now well 

 within the Weald and far removed from the chalk, 

 the gravel consists largely of iron-stained flints 

 closely resembling those well known in gravel 

 deposits on the downs, and among these there 

 are many waterworn " eoliths " identical with 

 those found on the chalk plateau near Ightham, 

 Kent. 



With the flints were discovered two fragments 

 of the molar tooth of a Pliocene elephant, and a 

 waterworn cusp of the molar of a Mastodon. The 

 gravel is therefore partly made up of the remains 

 of a Pliocene land-deposit. Teeth of hippo- 

 potamus, beaver, and horse, and part of the 

 antler of a red deer were also found, with several 

 unabraded typical early Palaeolithic (Chellean) 

 implements. The latter seem to determine the 

 age of the gravel as Lower Pleistocene. 



The human remains, which are in the same 

 mineralised condition as the associated fragments 

 of other mammals, comprise the greater part of 

 the brain-case and one mandibular ramus which 

 lacks the upper portion of the symphysis. The skii;l 

 measures 190 mm. in length by 150 mm. in width 

 at its widest part, and the bones are of nearly 

 twice the normal thickness. Its brain capacity is 

 about 1070 CO. The forehead is much steeper 

 than in the Neanderthal type, with only a feeble 

 brow-ridge; and the back of the skull is remark- 

 ably low and broad, indicating an ape-shaped 

 neck. The mandible, so far as preserved, is 

 identical in form with that of a young chimpanzee, 

 showing even the characteristically simian in- 

 wardly curved flange of bone at the lower border 

 of the retreating symphysis. The two molars 

 preserved are of the human pattern, but com- 

 paratively long and narrow. 



At least one very low type of man with a high 

 forehead was therefore in existence in western 

 Europe long before the low-browed Neanderthal 

 man became widely spread in this region. Dr. 

 Smith \Voodward accordingly inclines to the 

 theory that the Neanderthal race was a degenerate 

 offshoot of early man and probably became ex- 

 tinct, while surviving modern man may have 

 arisen directly from the primitive source of which 

 the Piltdown skull provides the first discovered 

 evidence. 



