B. TERRESTRIAL PHYSICS AND METEOROLOGY. 109 



is tlien set in rotation by rapidly spinning the cat-gut be- 

 tween the fingers, while at the same time the string and 

 featlier are slowly drawn up. By this means whatever air 

 adheres to the sides of the tube, or is carried down by the 

 quicksilver, is completely displaced and rises to the surface. 

 More mercury is then poured in, and the operation twice re- 

 peated, until the tube is filled. By this means a vacuum is 

 always secured without boiling the mercury in the tube, as 

 is shown by a comparison with the most carefully prepared 

 standard barometers. When the barometer is to be trans- 

 ported, the tube is emptied of mercury, which latter may be 

 carried either in the cistern or in a separate vessel. Yer- 

 handl. NaturJdst. Yereins, Bonn^ XXXI., 266. 



THE TEMPERATURE WITHIN THE GREAT GEYSER OF ICELAND. 



Mr. Robert Walker communicates to the Royal Society of 

 Edinburgh some measurements made in August, 1874, at the 

 Great Geyser of Iceland, which he visited, although his stay 

 was only for a few hours. During that time he was able to 

 make observations of temperature at twelve different depths, 

 varying from to 77 feet; and the temperatures at these 

 depths increased from 187 at the top to 257 at the bottom, 

 whereas the boiling-points, as calculated by him, w^ould have 

 been respectively 210 and 278 Fahr. He states that his re- 

 sults confirm very remarkably those of Professor Bunsen, ob- 

 tained during ten days in July, 1846. The difficulty of reach- 

 ing the place at all will hinder, he thinks, any one from car- 

 rying thither accurate apparatus for a more complete series 

 of observations than he was able to make. In a o-eneral 

 way he finds, as did Bimsen, that the temperature of the 

 water nowhere reaches the calculated boiling-point; but the 

 deviations therefrom seem to have been far irreater in 1846 

 than in 1874. 



No theory of internal caldrons filled in succession with 

 steam and water seems at all consistent with observed phe- 

 nomena. Proc. of the Royal Society of Edinburgh, WW., 

 514. 



AAVARD TO THE ARMY SIGNAL SERVICE. 



In noticing the fact that the recent Geographical Congress 

 at Paris awarded to the United States Army Signal Service 



