Miscellanies. * 199 



the fcistern being withdrawn, without disturbing that contained in the 

 tube. 



The boiler was set in brick work, in a proper position, over a small 

 fire-place. It was nearly filled with distilled water, which was made 

 to boil thoroughly, so -as to free it from air ; and the cock being then 

 closed, the water was raised in the tube, by the pressure of the steam 

 collected in the Upper part of the cistern. The tube, when filled, 

 was hermetically closed at the top : a proper scale, constructed by 

 Newman, was applied to it, great care being taken to determine its 

 height, and to ensure the accuracy of the adjustments and the pre- 

 cision of its measurements, by an exact mode of reading ; and also 

 to provide proper corrections for temperature. The water in the 

 cistern was protected from contact with the air, by being covered 

 with pure castor oil to the depth of half an inch. The mercurial ba- 

 rometer, employed as a standard of comparison, was of a portable 

 construction, and was provided with a platina guard. 



The register of observations of this instrument, given by the author, 

 and taken at least once a day, extend from October, 1830, to March, 

 1832. They afford some curious results. In windy weather, the 

 column of water is found to be in perpetual motion, not unlike that 

 from the breathing of an animal. Many considerable fluctuations on 

 the pressure of the atmosphere are rendered sensible, which would 

 totally escape detection by the mercurial barometer. The rise and 

 fall of the water precedes, by one hour, the similar motions of the 

 mercury. The most striking result of the comparison between the 

 two, is the very near coincidence of the elasticity of the aqueous 

 vapor as deduced from the experiments, with its amount as deter- 

 mined by calculation, in a range of temperature from 58° to 74°, 

 But a gradually increasing difference was. at length perceptible, 

 showing that gaseous matter had, by some means, insinuated itself 

 into the tube. When this became no longer doubtful, the boiler was 

 opened, and it was found that a portion of the liquid oil had escaped ; 

 and that the remainder had become covered with large flakes of a 

 mucilaginous substance, by means of which it is probable that a 

 communication had been established between the air and the water. 

 The water had, however, retained its purity, and no indication was 

 afforded of the metal having been any where acted upon. The 

 author recommends, that if these researches are prosecuted, the 

 water should be covered with a stratum of oil of four or five inches 

 in depth, which he has reason to think will form an effectual barrier 

 to all atmospheric influence. — Loud. Phil. Mag. Nov. 1832. 



