446 



NATURE 



\_March lo, 1881 



of hopeless difficnlty. Nevertheless we are able, by attending 

 to the condition of similarity of the motion in different cases, to 

 compare the viscosities of the different gases for as many groups 

 of corresponding pressures as we please. Setting a-ide certain 

 minute corrections which would have vanished altogether had 

 the moment of inertia of the vibrating body been sufficient to 

 make the time of vibration sensibly independent of the gas, as 

 was approximately the cafe, the condition of similarity is that 

 the densities shall be as the log decrements of the arc of vibra- 

 tion, and the conclusion from theory is that when that condition 

 is satisfied, then the viscosities are in the same ratio. Pressures 

 which satisfy the condition of similarity are said to "corre- 

 spond." 



It was found that on omitting the high txhaustions, the 

 experiments led to the following law : — 



The ratios of the viscosities of the different gases are the same 

 for any two groups of corresponding pressures. In other words, 

 if the ratios of the viscosities of a set of gases are found (they 

 are given by the ratios of the log decrements) for one set of 

 corresponding pressures, these pressures may be changed in any 

 given ratio without disturbing the ratios of the viscosities. 



This law follows of course at once from Maxwell's law, 

 according to which the viscosity of a gas is independent of the 

 pressure. It does not however by itself alone prove Maxwell's 

 law, and might be satisfied even were Maxwell's law not true. 

 The constancy however of the log decrement, when the circum- 

 stances are such that the molar inertia of the gas may presumably 

 be neglected, proves that at any rate when the density is not too 

 great that law is true ; and the variability of the log decrement 

 at the higher pressures in all but the very light gas hydrogen is in 

 no way opposed to it, though Mr. Crookes's experiments do not 

 enable us to test it directly, but merely establish a more general 

 law, which embraces Maxwell's as a particular case. 



The viscosities referred to air as unity which came out from 

 Mr. Crookes's experiments were as follows : — 



Oxygen ril? 



Nitrogen and carbonic oxide 0'970 



Carbonic anhydride o'823 



Hydrogen 0-500 



The viscosity of kerosoline vapour could not be accurately 

 deduced from the experiments, as the substance is a mixture, 

 and the vapour-density therefore unknown. Assuming the relative 

 viscosity to be o'03So, the vapour-density required to make the 

 experiments fit came out 3'4o8 referred to air, or 49'l6 referred 

 to hydrogen. 



When once the density is sufficiently small, the log_decrement 

 may be taken as a measure of the viscosity. Mr. Crookes's 

 tables show how completely Maxwell's law breaks djwn at the 

 high exhaustions, as Maxwell himself foresaw must be the case. 

 Not only so, but if we take pressures at those high exhaustions 

 which are in the same ratios as " coiTesponding '' pressures, the 

 log decrements in the different gases are by no means in the 

 ratios of the densities. 



It would appear as if the mechanical properties of a gas at 

 ordinary pressures and up to extreme exhaustions (setting asiile 

 the minute deviations from Boyle's law, &c.) were completely 

 defined by two constants, suppose the density at a given pres- 

 sure and the coefficient of viscosity ; but that specific differences 

 come in at the high exhaustions at m hich the phenomena of 

 "ultra-gas" begin to appear; and that to include these, an 

 additional constant, or perhaps more than one, requires to be 

 known. 



ANIMAL REMAINS IN THE SCHIPKA 

 CA VERN 

 C\^ December 6, iSSo, Prof. Schaaffhausen gave a lecture to 

 ^^ the Lower Rhire Society in Bonn, on the discoveries made 

 by Prof. Maschke in the Schipka Cavern, near Stramberg, in 

 Moravia. In this cavern were found remains of Bos, Ursus, 

 Elephas, Rhinoceros, Leo, and Hy^na, besides roughly-hewn 

 implements of quartzite, basalt, and' flint, and some incisor teeth 

 of Ursus, which were cut into on both sides at the beginning of 

 the crown, perhaps because people did not yet know how to bore 

 a hole into the root. Carbonised animal bones in numerrus 

 small fragments were met with. A solitary human relic was 

 found in a protected place at the wall of a side passage of the 

 cavern, and nenr a fireplace. It was the fragment of a lower 

 iaw, amid ashe-. and inter-breccia of lime. The same layer con- 



tained mammoth remains and stone implements. Of the jaw- 

 only the front part with incisors, one canine, and the two pre- 

 molars, of the right side remained. The latter three teeth were 

 still in the jaw undeveloped, but were visible, because the front 

 wall of the jaw was wanting. The largeness and thickness 

 of the jaw, first of all, were remarkable. The teeth-development 

 corresponds to the first year of life, but the jaw and the teeth are 

 as large as those of an .adult. As is the rule with man, the first 

 pre-molar seemed nearest being cut ; next to it came the canine, 

 then the second pre-molar. 



The height of the jaw in the line of symphysis measures, to 

 the alveolar border, 30 mm., to the end of the incisors 39 mm. 

 (In the jaw of a child seven years old the corresponding measure- 

 ments were 23 mm. and 30 mm. ; in a girl nine years old 24 mm. 

 and T,^ mm. ; in a boy of 12, 22 mm. and 31 mm. The jaws of 

 eight adults measured in height, to the alveolar border, on an 

 average, 31 mm.) The jaw fragment, at its lower border, in the 

 line of symphysis, is 14 mm. thick ; under the canine tooth the 

 thickness is 15 mm. (In an ordinary adult jaw the thickness in 

 the line of symphysis is about n mm.) Now when the cutting 

 surface of the incisors is placed horizontally, the under part of 

 the prognathous jaw bends so much back that one misses the 

 chin as a prominence. A vertical from the front alveolar border 

 falls 4 to 5 mm. in front of the lower border of the jaw. The 

 hinder surface of the symphysis is placed obliquely, as occurs in 

 a high degree in the anthropoids, and in lower degree in savage 

 races, but has also before been observed in fossil human remains, 

 as in the jaw of La Naulette, to which this jaw from the Schipka 

 Cavern has much similarity. The form of the incisors is 

 adapted to the thick prognathous jaw ; the broadest part of the 

 root measures from front to back 84 mm., whereas the ordinary 

 measurement here is 6 rem. Further the teeth are bent convex 

 in front. The curvature corresponds to a radius of 27 mm. 

 The spi?ia mentaUs inlerna is absent, and instead there is, 

 as in the anthropoids, a cavity, at the lower border of which 

 some unevenness can easily be felt. The prominences for 

 attachment of the MuscuH digasirici are well marked, implying 

 a correspondingly strong development of the antagonistic 

 muscles, the masticatory. All these features were also met with 

 on the jaw of La Naulette, but more developed. It is probable 

 that the jaw of the Schipka Cavern also had the pithecoid pecu- 

 liarity, that its tooth-line was not horizontal, but rose from the 

 premolars to the incisors, and its body was higher in front than 

 at the sides, because the cutting-surface of the outer inci'ors 

 sinks obliquely outwards. The size of the canine tooth is re- 

 markable, its enamel crown being I3-5 mm. long. (In the fossil 

 lower jaw of L'elde the canine tooth exceeds the premolars about 

 3'5 mm. According to measurement on ten European adult 

 skulls with the teeth hardly, or not at all, worn down, the crown 

 of the canine tooth was 11 -5 mm. long. Only once, among more 

 than fifty skulls, was it found 14 mm.) It cannot well be sup- 

 posed that this jaw, caught in dentition, belonged to an individual 

 of giant growth, since in such individuals the excessive growth, 

 according to Langer, first begins about nine to ten years of age. 

 The assumption that some pathological cause had hindered the 

 development of the three teeth that remained within the jaw 

 seems quite groundless. As little can we suppose that in the 

 prehistoric time the teeth development was retarded, and that 

 the change of teeth occurred at a later age, since a quicker deve- 

 lopment corresponds to a lower organisation. (All mammals 

 come into the world with teeth, and the orang changes its teeth 

 sooner than man.) 



The size of the front part of the jaw however may in itself 

 be regarded as pithecoid ; and there is more reason for this in 

 that other pithecoid characters are present. The aspect of the 

 grey-yellow bone with small dark branching spots on it is met 

 with often in cavern bones. The enamel of the teeth is quite 

 like that of the Quaternary cave animals ; it shows longitudinal 

 fissures with dark infiltration ; while near these appear bluish, 

 and in some places yellow, spots. 



SOME REMARKS ON PERIPATUS 

 EDWARDSII, BLANCH. 



SINCE I learnt from Mr. Moseley's notes on the species of 

 Pcripatus {Ann. aiui Mag. of Xat. Hist.,y. ser., iii., 263), 

 that one of them, referred by Grube to P. Ed-wardsii, had been 

 obtained from this country, in the neighbourhood of Colony 

 Tovar^), I tried to get specimens of this highly mteresting 

 ' Not Colony Jozuar, as the name is printed in Mr. Moseley's paper. 



