B. TERKESTRIAL PHYSICS AND METEOROLOGY. 1 1 7 



examination of aneroids under the receiver of an air-pump 

 has been attempted by Stewart and by Lovering ; the com- 

 parison of an aneroid with a quicksilver barometer, by carry- 

 ing both together to high altitudes, has been attempted, 

 among others, by IToltschl. But all these attempts are un- 

 satisfactory, and Schreiber has substituted therefor the fol- 

 lowing: method : An iron receiver is made, in which the 

 aneroid is placed, and which can be closed hermetically by 

 a glass plate. The receiver is then connected with a ma- 

 nometer, so that air can flow in, and furnished with a stop- 

 cock, so that air can flow out. The changes of pressure of 

 the air within the receiver are brought about by chang- 

 ing the temperature, which may be elevated to 50 Centi- 

 grade, or cooled to 20, by which means pressures of 

 from 730 to 570 millimeters can be attained. At the higher 

 temperatures successive gradations of pressure are obtained 

 by allowing the expanded air within to escape little by little 

 through the proper cock. In a second paper, Schreiber con- 

 siders the influences of changes of gravity upon the differ- 

 ence between the aneroid and the mercurial barometer, in 

 which he combats the somewhat absurd theories of Herr 

 von Wullerstorff'-Urbair, who, besides a correction for grav- 

 ity, suggests also a correction for terrestrial magnetism. 

 The unimportance of the latter correction is proved by 

 Schreiber, by simply causing the steel index-needle of the 

 aneroid to be strongly magnetized, in which condition, 

 however, no alteration took place in the reading of the in- 

 strument. The latest forms of construction of the aneroids 

 suggested by Kohlrausch, Weilenmanu, and Reitz are also 

 elucidated by Professor Schreiber. 



In a third communication, Schreiber explains a method of 

 using the results published by Ruhlmann on barometric hyp- 

 sometry, showing that in Saxony, at least, hypsometric 

 measurements can be made without determining the tem- 

 perature of the air at the time of observation, but by using 

 the mean daily temperature. 



In a fourth communication, Schreiber treats of the differ- 

 ences between the pressure of the air in buildings and in the 

 open air, as brought about through the suction or pressure 

 produced by the wind blowing into or past open windows. 

 Similar eff*ects have been observed and studied by James 



