May 31, 1907] 



SCIENCE 



843 



getting the height of clouds at Blue Hill. 

 Colonel Vives y Vich recommended sending 

 up paper pilot balloons simultaneously 

 with the ballotis-sondes in order to see how 

 the wind changed in the isothermal zone. 

 Baron von Bassus exhibited an apparatus 

 for reading the curves of the self-recording 

 instruments and Dr. de Quervain discussed 

 the thermal inertia of the different ther- 

 mometers, concluding that the metallic bar 

 of Hergesell was more sensitive than that 

 of Teisserenc de Bort. An interesting dis- 

 cussion followed as to the relative value of 

 observations obtained with kites and bal- 

 loons, General Rykatehef, Professor Berson 

 and others favoring the former and Pro- 

 fessor Hergesell alone championing the 

 latter method. 



General Rykatehef, for Mr. Kouznetzof, 

 explained a method that had been employed 

 at Pawlowsk to ascertain the height of 

 clouds at night by projecting a searchlight 

 upon them and measuring the vertical 

 angle of the spot of light, which elicited the 

 information that the same method had been 

 tried in Prance, at Hamburg and at Blue 

 Hill. Captain Scheimpflug showed how 

 photographs of the ground taken from a 

 balloon could be rectified so as to be trans- 

 formed into topographical plans. 



A number of communications giving the 

 results of observations in the free air were 

 presented. General Rykatehef stated de- 

 ductions concerning the vertical gradient 

 of temperature in the free air at Pawlowsk, 

 which is greatest near the ground and dur- 

 ing the month of June and least in Decem- 

 ber. Another paper by Dr. Rosenthal dis- 

 cussed the diurnal range of temperature 

 at different heights over the sea. While in 

 the first 100 meters there is a fall of 1° C. 

 in the day and 0.2° at night, in the stratum 

 between 300 and 400 meters the decrease 

 is 0.6° during both day and night. 

 Mr. Rotch gave the results of the first 



hallons-sondes in America, fifty-three of the 

 fifty-six balloons which he had despatched 

 from St. Louis in 1904- '06, having been 

 recovered. One of the lowest temperatures 

 ever observed (—79° C.) was recorded in 

 January at a height of only 14,800 meters, 

 and the isothermal, or relatively warm 

 current, which had been found in Europe, 

 was shown to exist at a greater height in 

 the United States. Dr. de Quervain pre- 

 sented proofs of this isothermal stratum 

 above 12,000 meters, which had been fur- 

 nished by ascents of balloons in the day- 

 time. Professor Hergesell related some 

 experiments which he had made to measure 

 the vertical movement of the atmosphere 

 by getting the difference between the cal- 

 culated rate of ascent of the balloon and 

 the vertical movement of the air recorded, 

 amounting in one case to a dov/nward cur- 

 rent of half a meter per second. Professor 

 Berson offered two papers, one being a 

 discussion of more than a thousand kite 

 flights at Lindenberg, in order to ascer- 

 tain the variation of wind-velocity with 

 height, the author concluding that the 

 velocity increases faster than the density 

 of the air decreases. The other paper dis- 

 cussed the data from sixteen hallons- 

 sondes, sent up from Milan the previous 

 summer, nine of which could be followed 

 in the telescope to a distance of eighty 

 kilometers. Very low temperatures were 

 recorded, and — 64° C. at 12,000 meters 

 corresponded to a change of 100° C, from 

 sea level, or nearly the adiabatie rate. 

 Mr. Dines showed views of the kite wind- 

 lass used by Mr. Cave and gave an ex- 

 ample of a large inversion of temperature 

 observed in England up to 2,000 meters. 



The most interesting communications re- 

 lated to the exploration of the atmosphere 

 over the ocean during the preceding year. 

 M. Teisserenc de Bort gave the results of 

 the last cruise of his steam-yacht Otaria, 

 which had been sent across the equator by 



