80 abstracts: navigation, atmospheric electricity 



Inasmuch as one important use of this catalogue will be in the statisti- 

 cal study of proper motions, since for many of these stars these are the 

 earliest observations ever made, it was highly desirable to determine 

 corrections which would reduce the system of the catalogue of reference, 

 the Cordoba General Catalogue of 1875, back to 1850 the epoch of this 

 catalogue. This was done by making a comparison between the Cordoba 

 General Catalogue and the Cape Catalogue of 1850, and the systematic 

 corrections resulting from this investigation have been applied so that 

 the positions in this catalogue are virtually those which would have been 

 obtained by the use of a reference catalogue of its own epoch. The sys- 

 tem of this catalogue is therefore that of the Cape Catalogue of 1850. 



F. B. LlTTELL. 



NAVIGATION. — Daylight observations on Venus. J. P. Ault Bulle- 

 tin American Geographic Society. October, 1911. 

 The writer gives a summary of his experience in making daylight ob- 

 servations on Venus as navigating officer on board the Carnegie, the 

 magnetic survey yacht of the Carnegie Institution of Washington, during 

 her first cruise in the North Atlantic, 1909-1910. The usual instru- 

 ments and methods used in making observations on the Sun were em- 

 ployed in observing on Venus. Tabulations of observations both for 

 latitude and longitude are given. The observations for latitude were 

 usually made by two and sometimes by three observers and the results 

 never differed by more than 0.5 minute of arc and usually agreed within 

 0.1 minute. The observations for longitude also indicated that uni- 

 formly good results can be obtained. The novelty of observing a star 

 by daylight adds enough interest to the work of the navigator to warrant 

 undertaking the operation without any other inducement, but there is 

 added to this at least two opportunities for an accurate determination 

 of the ship's position entirely independent of the operation of dead reck- 

 oning. J. A. Fleming. 



ATMOSPHERIC ELECTRICITY.— Atmospheric electricity observa- 

 tions on the second cruise of the " Carnegie," from New York to Col- 

 ombo. Edward Kidson. To appear in the Journal of Terrestrial 

 Magnetism and Atmospheric Electricity. 

 This paper gives tabulations together with a synopsis of the observa- 

 tions taken for the specific conductivity of the atmosphere, radioactivity, 

 and potential gradient of the atmosphere, as determined on board the 

 Carnegie on her second cruise between New York and Colombo during 



