NATURE 



[May 30, 1907 



The three principal days of the series are July 23, 24, 

 and 25, but where possible ascents will also be made on 

 July 22, 26, and 27. All the observatories engaged in 

 upper-air research will take part. In addition, the Prince 

 of Monaco will make observations in a high northern 

 latitude, and a German man-of-war will send up haXlons- 

 sondes between Iceland and Norway. Another German ex- 

 pedition, under Captain Hildebrandt, will go to the neigh- 

 bourhood of the Hebrides, while a French man-of-war will 

 be stationed near the Azores. Further south, M. Teisserenc 

 de Bort and Mr. Rotch will send an expedition, in their 

 yacht Otaria, to the region of the trade winds and 

 doldrums. It is hoped, also, that the Italian Government 

 will cooperate by sending a man-of-war to some point in 

 the Mediterranean. With the addition of Blue Hill 

 Observatory and other North American stations, there will 

 thus be a net-work of observations over a large region of 

 the northern hemisphere. 



In this country Mr. W. H. Dines will send up ballons- 

 sondes and pilot balloons at a station on the west coast 

 of Scotland ; ballons-sondes and pilot balloons will also 

 be sent up at Manchester by Mr. Petavel, and at Ditcham 

 Park, Petersfield. Conditions in this country at th'e end 

 of July are not likely to be favourable for flying kites, 

 but should there be sufficient wind kites will be flown 

 at Glossop Moor, Pyrton Hill, Ditcham Park, and 

 Brighton. 



The Royal Meteorological Society is also making 

 arrangements to cooperate in the investigations, and an 

 allowance (in aid of the expenses) has been made to them 

 from the Government grant for scientific investigations. 



It may be possible to obtain the assistance of other 

 observers to send up pilot balloons ; by the use of two 

 theodolites and a measured base, the velocity and direction 

 of the wind and the heights of clouds may be determined. 

 By using rubber balloons and filling them to a certain 

 size corresponding to a known rate of ascent, useful 

 observations may be made by a single observer using an 

 ordinary theodolite. 



The International Commission has also arranged for a 

 series of observations on September 4, 5, and 6, and on 

 November 6, 7, and S. 



Charles J. P. Cave. 



Radium and Geology. 



The temperature of 55° C. to which I referred in a 

 •former letter is the temperature of the rock. I find that 

 Prof. C. Schmidt, of Basel, on his chart of isogeotherms, 

 gives this temperature as attaining 56° C. This is in the 

 dry part of the tunnel, towards the north end. 



The difficulty attending the inflow of warm water 

 mainly arose from the rate at which heat was thereby 

 brought into the tunnel, necessitating large supplies of 

 cold water to keep down the temperature. Prof. Schardt's 

 paper, to which I have already referred, contains very 

 strong evidence as to the rdle of the circulating water. 

 The evidence is far too lengthy to quote here. 



Mr. Fisher refers to the Hon. R. J. Strutt's estimates 

 of radium in rocks as capable of accounting for a gradient 

 of 1° F. in 424 feet. In point of fact, Mr. Strutt assumes 

 this gradient (quoting from Prestwich) as a basis upon 

 which to calculate the thickness of the radium-bearing 

 trust. The gradient in question is, therefore, not derived 

 from Mr. Strutt's observations (nor could it be), but is a 

 gradient taken as a basis of calculation. 



That special conditions afi'ect the temperature gradients 

 in mountain ranges appears from the results of observ- 

 ations on the Mont Cenis and the St. Gothard tunnels. 

 Everett's estimate for the former, with correction for con- 

 vexity of surface, is 1° F. in 79 feet. In the case of the 

 latter (here were remarkable variations observed, of which 

 radium will very probably furnish the explanation. The 

 central gradient is 1° F. in 85 feet, .^t the north end 

 there is a gradient of 1° F. in' 38 feet. This brings the 

 general average for the whole tunnel up to 1° F. in 

 57-8 feet. Dr. Stapff, who conducted the temperature 

 observations in the St. Gothard, subsequently predicted for 

 the Simplon a maximum rock temperature of 47° C, as 

 I have already pointed out. J. Joly. 



Trinity College, Dublin. 



NO. 1 96 I, VOL. 76] 



AERIAL LOCOMOTION. 



IN December of last year Dr. Alexander Graham 

 Bell delivered an addre.ss, under the above title, 

 before the Washington Academy of Sciences. This 

 address recently appeared in the March number of the 

 Proceedings of that academy 1 (vol. viii., pp. 407-448), 

 and the interesting nature of the contents is well 

 worth the attention of the readers of this Journal who 

 have not had the opportunity of perusing it. 



In the opening paragraphs Dr. Bell refers to the 

 earlier attempts made to travel in the air, and points 

 out how the problem in the last decade or so has 

 gradually been approached from a different point of 

 view. The principle of the gas bag has taken second 

 place, and the heavier-than-air type of machine is 

 now in the forefront. 



The researches of Lilienthal are next referred to, 

 followed by those of Chanute, Herring, the Brothers 

 Wright, and Hargrave. The magnificent work 

 accomplished by Langley is here given its proper 

 position. "To Prof. Langley," as Dr. Bell remarks, 

 " is due the chief credit of placing this subject upon a 

 proper basis, and of practically originating what he 

 termed the art of ' x^erodromics. ' " 



Dr. Bell witnessed the experiments made by 



Fig. I.— Langley s Aerodrome No. ;, in riignL May 6, itoL. 



Langley on May 6, 1896, when a large model of an 

 aerodrome, with a spread of wing of about 14 feet, 

 was driven through the air by a steam engine under 

 the action of its own propellers. With regard to 

 the actual flight he saw, he wrote : — " No one who 

 witnessed the extraordinary spectacle of a steam 

 engine flying with vifings in the air, like a great 

 soaring bird, could doubt for one moment the prac- 

 ticability of mechanical flight." Dr. Bell was 

 fortunate enough to secure a photograph of the 

 apparatus while in the air, and this record, which is 

 reproduced in his article, is here given (Fig. i). In 

 time it will undoubtedly be of exceptional historical 

 interest. 



The circumstances connected with the later experi- 

 ments of Langlev are next described, and Dr. Bell's 

 knowledge and great faith in Langley 's work allow 

 him to state his unbiased opinion that the full-sized 

 aerodrome, which the newspapers described as a 

 failure, " would have flown had it been safely 

 launched into the air." 



It is with regret, however, that we find no mention 

 made of either Hiram Maxim or Pilcher, for the 



1 See also Tie National Geographic .Magazine, vol. xviii.. No. i. 

 January. 



