August 13, 1909] 



SCIENCE 



195 



cui'rent reinforces the downward draught, 

 then the instrumental error may be as- 

 sumed to be nil. Compressed air, con- 

 tained in a globe of polished metal, is lib- 

 erated against the thermometrie strip dur- 

 ing ten minutes by means of an aneroid 

 barometer at the height when the inversion 

 of temperature usually begins in cyclonic 

 or anti-cyclonic conditions. This device 

 has not yet been tried in the high atmos- 

 phere. The second part of Dr. Assmann's 

 paper described an apparatus for ventila- 

 ting thermometers in captive-balloons, es- 

 pecially during cakn weather. A horizon- 

 tal fan is driven by an electric battery, and 

 a dipping-vane changes its direction of 

 rotation when the descent begins. 



In discussing the first subject, the presi- 

 dent asked to have it noted that in spite of 

 incredulity in some quarters regarding the 

 reality of the upper temperature inversion, 

 no member of this commission doubted its 

 existence. 



Professor Hergesell exhibited a new 

 meteorograph for manned and captive-bal- 

 loons having a bimetallic blade for tem- 

 perature and a Vidi vacuum box for pres- 

 sure, with an automatic ventilator for the 

 former. This instrument made by Bosch, 

 of Strassburg, weighs 1,200 grams and 

 costs $75. A discussion followed as to the 

 use of a straight bimetaUie blade instead of 

 a curved one. 



Professor Palazzo, of Eome, described 

 two devices for launching hallons-sondes at 

 sea, in which the Bourdon barometric tube 

 liberates one of the tandem balloons or lets 

 out the gas. In discussing the necessity 

 of limiting the time of the ascensions other 

 devices for the same purpose were men- 

 tioned. 



Professor Eotch urged the adoption of a 

 uniform method of publishing the kite data 

 and suggested the form used at Blue Hill 

 and Mount Weather. He pointed out the 



confusion regarding the positive and nega- 

 tive sign attached to the temperature gra- 

 dient in the official publication of the data 

 derived from balloons and kites. Follow- 

 ing the report of a committee appointed to 

 consider the matter, the conference decided 

 to express the gradient as positive when 

 the temperature decreased with altitude 

 and, in the published kite-observations, to 

 give the simultaneous observations at the 

 groimd so far as possible. 



Professor Koppen, of Hamburg, sent a 

 memoir in which he proposed that, instead 

 of the usual readings of the barometer, the 

 data be expressed in absolute units of the 

 C.G.S. system, and that the pressure be 

 reduced to a height of 100 meters instead 

 of to sea-level. This proposition was re- 

 ferred to the International Meteorological 

 Committee. 



Professor Bjerknes, of Christiania, read 

 a paper on the theoretical application of 

 upper air observations, in which he insisted 

 that the object of aerological observations 

 is to secure diagnoses about the momentary 

 dynamic condition of the atmosphere. The 

 series of ascensions should give data sepa- 

 rated by such intervals as wiU permit the 

 changes occurring between different diag- 

 noses to be followed, so that by combining 

 them it becomes possible to formulate laws 

 by which the future state of the atmosphere 

 may be predicted. He proposed to estab- 

 lish three diagnoses, namely, in the morn- 

 ing, at noon and in the evening, or at 

 eight, one and seven o'clock, Greenwich 

 time, but as the instrumental equipment 

 will not permit all the diagnoses to be 

 complete, that at noon is declared the 

 principal one. At this moment kites and 

 balloons with instruments are to be sent up 

 and observations made at the ground which 

 will enable the atmospheric conditions at 

 different heights to be traced on charts. 

 For the morning and evening diagnoses, 



