40 



i 



Petersbourg par divers Savans, etlus dans ses Assemblies. Tome 

 premier; Ire, 2me, 3me, et 4me livraison. 4to. — The Academy. 



Rapport sur un Voyage dans les Environs du Mont Elbrouz, dans le 

 Caucase. Par M. Kupffer. 4to. — The Academy. 



Astronomische Nachrichten. No. 177-193. 4to. — Professor Schu- 

 macher, Foreign Member, R.S. 



A paper was read, entitled " Description of a Mountain Baro- 

 meter, the column of which is divisible into two portions for safer 

 and more convenient transport." By Mr. Thomas Charles Robin- 

 son. Communicated by Captain Henry Kater, F.R.S. 



The object of the contrivance described in this paper is to re- 

 duce the length of the barometer, when not in use, to one-half the 

 usual length ; and to render the position in which it may be carried 

 indifferent. It consists of a glass tube eighteen inches long, ce- 

 mented into a steel cistern two inches long, and one inch internal 

 diameter, which is furnished with an internal screw, for receiving 

 a hardened steel screw and hemisphere cemented to the end of a 

 syphon tube. The long leg of this tube has an internal diameter of 

 only the six or eight hundredths of an inch, and it is further con- 

 tracted at the end to the twenty-fifth of an inch, so that no air can 

 pass when the mercury is descending through it. The shorter leg 

 of the syphon has the same bore as the tube. 



When the two parts are screwed together, and the whole invert- 

 ed, the mercury descends from the cistern, fills the long leg of the 

 syphon, and ascends to a certain height in the shorter leg. Any 

 air that may have existed in that part of the cistern which was not 

 occupied by the mercury, is collected in an intermediate space, ex- 

 ternal to the column of mercury, and therefore can have no influ- 

 ence on the total height of that column, which is determined solely 

 by the pressure of the external atmosphere. On gently reversing 

 the position of the barometer, the mercury will repass from the 

 syphon into the cistern, where it is confined by a stopper, as in a 

 bottle: and may then be carried about in any position in perfect 

 security. 



The reading of a paper, entitled " An Account of further Expe- 

 riments tried at Chatham, for the purpose of obtaining an artificial 

 Water Cement," by Brevet-Colonel C. W. Pasley, of the Corps of 

 Royal Engineers, F.R.S. and Honorary Member of the Institution 

 of Civil Engineers, was commenced. 



The Society then adjourned over Easter to the 14th of April. 



April 14. 



HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, K.G., 

 President, in the Chair. 



Joseph Hodgson, Esq, was elected a Fellow of the Society. 



