94 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



title, published in 1865; but in the matter of rainfall Stud- 

 nicke has had special opportunities which have enabled him, 

 to say nothing of the lapse of the past ten years, to present 

 the fullest particulars and material. Thirty-eight stations 

 were indeed represented in the memoir of Sonklar on the 

 hyetography of Austria ; he was, however, unable, even with 

 this number of stations, to properly represent the southeast- 

 ern portion of Bohemia. The gaps that were necessarily 

 found in Sonklar's and Kreil's works have been filled up by 

 Studnicke, who was three years ago put in charge of the 

 meteoroloo-ical section of the committee for the scientific 

 survey of Bohemia, and who has been instrumental in adding 

 about fifty new stations to those already existing. Especial 

 study was made in the neighborhood of Prague, where four 

 new stations were established, in order to elucidate the dif- 

 ferences in the records of the older observations. Sitzh. Il 

 JBohm. Gesellschaft, 1874, 62. 



MOISTURE IN THE ATMOSPHERE. 



Marie Davy states that there is kept in active service in 

 the meteorological observatory at Mont-souris a collection 

 of apparatus for investigating, in a general way, certain 

 23hysical problems of the atmosphere, especially the quantity 

 of aqueous vapor contained therein. The apparatus consists 

 principally of a large telescope, with silvered objective and a 

 photometric ocular. This ocular consists of a Foucault po- 

 larizing prism, behind which is placed a double-refracting an- 

 alyzer movable about the centre of a graduated circle. By 

 the use of this apparatus we measure the ratio of the intensi- 

 ty of the light given from the sun, and from any part of the 

 atmosphere in its immediate neighborhood; this ratio varies 

 with the state of the sky. A similar operation would give 

 the measure of the apparent intensity of the solar spots. A 

 second telescope of smaller dimensions is mounted equatori- 

 ally. Its objective is uncovered, and its ocular is similar to 

 the preceding. A disk of white enamel is fixed horizontally 

 on a pillar; at the side of the disk is found a smaller one of 

 copper, which projects its shadow upon the enameled disk 

 w^hen illuminated by the sun. This shaded circle is then 

 only lighted by the diffused light of the sky, while the neigh- 

 boring parts receive also the direct rays of the sun. The 



