February ii, 1909J 



NATURE 



429 



lying portions of the ill-fated cities and the Calabrian 

 v'illages once stood. It is a warninj^ to those who may be 

 in any way responsible for rebuilding them. 



A. Irving. 

 Bishop's Stortford, January 21. 



The Isothermal Laytr of the Atmosphere. 



Mk. Dines makes a happy choice of terms when he 

 writes of the isothermal column (Nature, January 21, 

 p. 3^I). Each of the unrejected traces is interpreted to 

 show a more or less isothermal column, and it is by 

 mentally piecing together these columns into a sort of 

 honeycomb that the miscalled isothermal layer is brought 

 into existence. It must not be forgotten that this hypo- 

 thetical layer has a very uneven floor, and that each cell 

 in the honeycomb has its own particular temperature. 

 This is a complex structure. I certainly think it more 

 feasible to ascribe the sudden and sustained minimum in 

 the temperature curve, which is the gist of this discussion, 

 to some idiosyncrasy or limit to which all the instruments, 

 foreign as well as native, are subject night and day, and 

 on the down as well as the up journey. In your issue of 

 January 21 I referred to the falling density of the air 

 current, upon which current the whole experiment depends. 

 If the trace shows a uniform temperature during the upper 

 9 kilometres of an ascent, there is no escape from the 

 conclusion that the temperature of the air has steadily 

 fallen to compensate for its tenuity, and if we assume an 

 adequate compression of the hydrogen before the rubber 

 gives way, there is a further compensation required for 

 loss of speed. 



I shall now endeavour to answer Mr. Dines 's points 

 by the help of the old-fashioned laws of heat. 



" The isothermal column of air shows just as plainly 

 in ascents made after sunset as in those made in the day." 



Yes. Radiation is stronger by day, but radiation and 

 convection balance at some point, and the balance, if main- 

 tained, means a regular fall of temperature upwards. 



" .At night the thermograph must receive some heat bv 

 radiation from the earth, and lose some by radiation into 

 space, but both amounts must be infinitesimal in com- 

 parison with that which would be given to it by the sun." 



Being quite close to the hot planet, and being far below 

 the temperature due to such proximity, the balloon, &c., 

 win rireive more radiation than they emit. The radiation 

 from the planet, subtending nearly a hemisphere, will be 

 far from infinitesimal compared with that of the sun. 



" That solar radiation in the ordinary conditions is not 

 important is proved by the fact that if the balloon bursts, 

 and therefore does not float, it is not possible to say from 

 the trace alone if the ascent was by night or by day." 



If solar radiation cannot be detected on the traces it 

 must be because they differ so much inter se. Surelv if 

 aeration is so good for the thermograph it must be equally 

 good for the balloon, and a perfect torrent of warmed air 

 must waft on to the instrument during the ascent. 



" There have been cases in which the balloon did not 

 burst, and the temperature at the top reached the freezing 

 point of water." 



This shows an approach to what I call the natural 

 temperature of a body bctw^een the sun and a warm planet. 

 Of course, the balloon, instrument, &c., would have been 

 much hotte^-_ out of contact with the cold air which was 

 basking in the sunshine at a temperature of about 100° F. 

 below freezing. This recalls the question with which I 

 finished my last letter. 



" I still believe that radiation at night to and from 

 the bright metal of the thermograph is so trifling that 

 the rate of ascent is of no consequence." 

 ■ The whole apparatus is admirably contrived — let us try 

 faithfully to decipher the trace it gives us. The thermo- 

 graph is scores of degrees below its natural temperature. 

 This argues an intake of heat by absorption of ravs. which 

 heat is taken by the air current. The current must be 

 colder or more rapid at the 20-kilometre level to give the 

 traces that are now under discussion. 



"There is also the fact that the up-trace, where the 

 motion is comparatively slow, is identical with the dow^n- 

 trare where the motion is rapid." 



SO. 2050, VOL. 79] 



Mr. Dines has dispensed with a timepiece in many cases. 

 Can he speak positively as to the vertical speeds? If it 

 is quite clear that the down-speed is greater I can only 

 suggest that with a parachute the motion is partly lateral, 

 i.e. a gliding motion through the air, which would tend to 

 interfere with the draught, as would also the parachute 

 acting as a cover to the screen. Perhaps also the para- 

 chute subtends a larger angle than the balloon did. 



Summarising the matter, I contend that " isothermal 

 layer " is a misleading misnomer. 



The basaltic structure of the upper air which is inferred 

 from the traces is intrinsically improbable. 



To get the temperature of the air from the trace a 

 curve must be draw-n on its low-temperature side and 

 diverging upwards. 



The result will be a non-isothermal curve. 



The amount of this correction for all currents can be 

 determined on the instrument in the laboratory. 



R. F. Hughes. 



The Size of the Leather Turtle. 



.As trustworthy weights and measurements of large 

 turtles are not often available, the following measurements 

 and weight of a leather-back turtle, Sphargis, are sub- 

 mitted in the hope of eliciting further data regarding this 

 or other species. The total length of the animal, measured 

 along the curve from the nose to tail, was 6 feet 10 inches ; 

 the carapace along the curve, 5 feet 2 inches ; the circum- 

 ference at the widest part of the carapace, 7 feet 2 inches ; 

 from tip to tip of front flippers, over the shoulders, 8 feet 

 9 inches. Weight, a little more than 840 lb., for, when 

 on the scales, the tips of the large front flippers rested 

 on the ground. This is one of the largest turtles of this 

 species that has come under iny observation. Another 

 specimen that I was able to weigh turned the scales at 

 740 lb. F. A. Lucas. 



Museum of the Brooklyn Institute, Eastern 

 Tarkwav, Brooklyn, N.Y. 



Moral Superiority among Birds. 



In Natl're of January 7 Mr. F. C. Constable describes 

 an observation of the moral superiority of the blue-tit over 

 the robin. This is by no means exceptional. I constantly 

 observe the same thing from my dining-room window, 

 where I have a string stretched across with pieces of 

 cocoa-nut and pork-fat attached to it for the tits to feed 

 upon. In the cold weather the robins come too, but they 

 are never allowed to feed in company with the blue-tits ; 

 they are attacked at once if they venture to hold their 

 ground. The long-tailed tits and the cole-tits are much 

 less aggressive, and will even give way to the robins. 



Laura D. H. Dukes. 



23 Torrs I'arlc, Ilfracombe, February i. 



WOMEN AND THE FELLOWSHIP OF THE 



CHEMICAL SOCIETY. 

 TN our issue of July 9, 1908 (vol. Ixxviii., p. 226), 

 A we directed attention to the fact that an influen- 

 tially signed memorial had been presented to the 

 council of the Chemical Societj' stating- that, in the 

 opinion of the memorialists, 312 in number, including; 

 ten past presidents, twelve vice-presidents, and twenty- 

 nine members of council, among whom were thirty- 

 three Fellows of the Royal Society, and the heads of 

 the chemical departments of nearly all the most 

 important luiiversities and colleges in the Icingdom, 

 the time had come wiien duly qualified women should 

 be admitted to the fellowship of the society, and 

 praying that the council would take the necessary 

 steps to permit of their election. 



The council, having taken the memorial into con- 

 sideration, determined to consult the whole body of 

 the society, and instructed a committee to prepare 

 a statement of reasons for and against the proposal, 

 to be submitted, together with the memorial itself, to 



