390 



NA TURE 



[P'ebruaky 27, 1908 



the race, ;aul tliat E = E„ + /c(, where E, and fc are con- 

 stants. Calling E/i the rate of fatigue /, express this in 

 terms of J. . 



Assuming that an animal going at «„ miles per hour 

 frcls no fatigue, or when s = s„, /=o; find / in terms of .?. 



(i) Contains the general result; the law is that t is 

 proportional toj/^^or y^''-^. It may be stated in various 

 other ways ; for example, that the average speed in each 

 race is inversely proportional to the eighth root of y, or a 

 race 256 times as far is done at half the average speed. 



In short races there is increase of speed at the beginning 

 and almost always increase near the end ; and it may be 

 that there is continuous change of speed during all 

 record races. We have only average speeds recorded, 

 unfortunately, but still I must consider this wonderful 

 general law to be worthy of the attention of biologists. 

 (3) Contains a poor speculation of my own, good enough 

 for such an examination ; the answer to it is that / is 

 equal to E„c*(i' — j,°). There is nothing extraordinary in 

 the fact that record bicycle races do not follow the law ; 

 they have been run on machines of varying quality. 



The values of c found by Prof. Kennelly are, his 

 distances y being in metres : — trotting horse, 0-0295 ; 

 pacing horse, O'Oagi ; running horse, 00236; man running, 

 00588 ; man walking, 00S61 ; man skating, 0-0385 ; man 

 swimming, 0-381. Men rowing, four oars, 0-0628; two 

 oars, 0-0768 ; singles, 0-0824. John Perry. 



Royal College of Science, S.W. 



The Isothermal Layer of the Atmosphere. 



Thi: investigation of the upper air which has been in 

 progress during recent years has revealed conditions for 

 which it is very hard to find an explanation. When Mr. 

 Roicli first inaugurated observations on temperature and 

 humidity by means of kites, it was hoped that the results 

 oljtained would solve many problems connected with 

 meteorology, and this hope was strengthened when M. 

 Teisserenc de Bort greatly extended the height to which 

 observations could be made by his system of ballons 

 sondes. It has not, however, been realised, and we seem 

 to be as far as ever froni knowing the cause and 

 mechanism of the cyclonic storms that are so common in 

 the oceanic parts of the temperate latitudes. 



.Since last June some forty balloons have been sent up 

 in Great Britain, carrying with them a small instrument 

 which draws automatically a pressure temperature 

 diagram, and of these more than thirty have been re- 

 covered. The results confirm those previously obtained on 

 the Continent, and no doubt can now remain about the 

 existence of the curious isothermal layer in the atmosphere. 



Briefly, the more important phenomena are these. As 

 we ascend the temperature of the air decreases, at first 

 often irregularly, with breaks and inversions, but after the 

 first 10,000 feet (3 kilometres) have been passed with fair 

 regularity, the usual decrease being about 3°-3 F. per 

 1000 feet (6° C. per kilometre). This continues to a 

 height that varies, as a rule, from 30,000 feet to 40,000 

 feet. Nearly always at somewhere about this height the 

 decrease suddenly ceases. Above this point the air in most 

 cases gets a little warmer ; occasionally, however, it con- 

 tinues to get cooler, but at a totally different rate, and we 

 may take the remaining air to be at one practically 

 uniform temperature in so far as change of height is 

 concerned. This isothermal layer, as it has been called, 

 has been reached in England more than thirty times. On 

 the average its height is about 35,000 feet (10-7 kilometres), 

 but the extreme values found were 25,500 feet and 49,000 

 feet. .\s a rule, it is higher than the mean when the baro- 

 meter is high, and conversely. Its mean temperature was 

 found to be — 53°-6 F. ( — 47° C), and the extremes were 

 — 22° F., at Ditcham Park, Hants, on July 24; —24° F., 

 at Crinan, on July 26; —78° F., at Pyrton Hill, Oxford- 

 shire, on September 12, 1907, and also on February 5, 

 1908; and —74° F., at Manchester, on November 7, 1907. 



This mean value is considerably higher than the Con- 

 tinental one for previous years, but as thirty observations 

 do not suffice to give a true mean, this may be accidental. 

 Balloons have been sent up from five stations on the 

 same day, and the temperatures over the stations have 

 been found to differ widely. Thus on November 11 Mr. 



NO. 2000. vor. 77I 



Cave's balloon from Ditcham Park reached the isothermal 

 layer at 36,000 feet, and its temperature was —42° F. 

 Over Oxfordshire the height was 38,500 feet, and the 

 temperature —58° F., while at the same time, which was a 

 little after sunset, Mr. Petavel, at Manchester, found it at 

 37,000 feet, with a temperature of —74° F. This is not 

 an isolated instance, and although the heights given may 

 be uncertain to an extent of perhaps 5 per cent, or even 

 more, it is very unlikely that the error in the temperature 

 can exceed three or four degrees F. It may be accidental, 

 but the temperature over Ditcham Park, which is near 

 the sea, shows a tendency to exceed that over the Midlands. 

 The balloons mostly drift to the eastward, the centre of 

 their falling points being thirty-four miles E., 23° N., of 

 the starting point. Doubtless several of the unfound 

 balloons fell in the North Sea, as some have been returned 

 from France and Holland. 



Various suggestions have been made to account for these 

 results. There is, of course, no difficulty about the general 

 decrease of temperature with height, but why should the 

 fall suddenly cease when from one-third to one-fourth 

 of the mass of the atmosphere remains above? In 

 general, the transition point is perfectly sharp and distinct. 

 It is said that the vertical circulation ceases at this point, 

 and no doubt the statement is true, but why should it 

 cease? There is a further difficulty. The absence of 

 vertical motion implies a condition of equilibrium, but 

 how can there be equilibrium with such large horizontal 

 differences of temperature? At the height of 40,000 feet 

 the pressure is small, and therefore trifling changes of 

 pressure produce large changes of volume and tempera- 

 ture ; hence large changes of temperature might be ex- 

 pected if we could assume some horizontal force, com- 

 parable with gravity, and capable of producing changes 

 of pressure without producing vertical motion. The hori- 

 zontal acceleration due to centrifugal force in a curvilinear 

 path and that produced on a moving body by the earth's 

 rotation are too small ; also it seems to me that these 

 forces, being due to motion of the air, must produce some 

 vertical circulation, which apparently does not exist. 



The problem is one of the most interesting presented at 

 the present time to physical science, and it is not unlikely 

 that its solution might clear up many other puzzling 

 questions. W. H. Dines. 



The Inheritance of "Acquired" Characters. 



Mr. Archdall Reid in his previous letter said (p. 293) 

 " innate characters arise inevitably as the child develops, 

 whereas some acquirements are more or less rare, but thi^ 

 is only because the stimulus of nutriment is inevitably 

 received, whereas the stimulus of a particular tise or 

 injury may not be received. If, however, the latter be 

 received, the acquirement arises just as inevitably as tlu 

 innate characters." This latter statement seemed to me 

 particularly incorrect for the reasons which I stated ; and 

 now Mr. Reid practically admits (p. 342) that it cannot 

 be accepted as it stands, in face of the fact that the 

 inherent tendencies of the germs of different human beings 

 vary so much, and must therefore react variously to the 

 stimulus of use. 



My chief objection, however, to Mr. Reid's view was 

 that contained in his statement that " in man the main 

 difference between the infant and the adult is due to use 

 acquirements made by the latter during development." 

 His whole case in the discussion hinges upon this state 

 ment, by which he seeks to establish a purely arbitrary 

 distinction between the causes leading to the development 

 of the human being anterior to birth and subsequent to 

 birth — the stimulus in the one case, he says, being nutri- 

 ment, and in the other use. .'\s an illustration of his posi- 

 tion, Mr. Reid said (p. 293) : — " Thus, if the limb of an 

 infant be paralysed it grows comparatively little, and the 

 muscles atrophy." But this is by no means to be taken 

 as a simple illustration of the fact that the muscles will 

 not develop except under the stimulus of use, because the 

 illustration ignores the fact that what happens in the way 

 of retarded growth of the paralysed limb, together with 

 actual atrophy of muscles, is, quite apart from the lack of 

 use, largely due to a severance of the normal relations 

 between the limb and the great nerve centres, and the 



