1824.] Scientific Intelligence. 313 



Dr. Bree, FRS. President ; Dr. Paris, FRS. ; Dr. E. T. 

 Monro ; J. Brookes, Esq. FRS. ; W. T. Brande, Esq. FRS. ; 

 Sir J. Mac Gregor, MD. FRS.; Sir A. Crichton, MD. FRS. 

 Vice-Presidents ; W. Newman, Esq. Treasurer ; Mr. C. Hold- 

 stock, Secretary; J. Frost, Esq. Prof . of Botany ; T. Jones, 

 Esq. ; W. Yarrell, Esq. ; T. Andrews, Esq. ; A. White, Esq. ; 

 Dr. J. Elliotson. 



Article XVII. 



SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS 

 CONNECTED WITH SCIENCE. 



I. Improvement in the Mountain Barometer. 



Mr. Newman has proposed to remedy the inconveniences of the 

 common instrument: what rhese are, and the mode of removing them, 

 we shall give in his own words : — 



" The object has been to correct those defects and errors which arise 

 from the use of a wooden cistern and leather bag, in the common 

 barometer. It has been found that when the cistern is made of a wood 

 sufficiently sound and close-grained to permit of the pressure required 

 from the screw to make the instrument portable, that it is so imper- 

 vious to air, as not to allow it to pass with sufficient freedom, and con- 

 sequently, that when the instrument is used at any great altitude, the 

 mercury cannot fall into the cistern except with considerable difficulty, 

 and a long time is required before an accurate observation of the air's 

 pressure can be made; most generally, however, the cistern is suffi- 

 ciently pervious to air, but it is then found that on screwing up the 

 mercury to the top of the tube, a portion of the metal generally makes 

 its' way through the wood, thus soon rendering the instrument quite 

 useless ; for it is very evident that a barometer that loses a portion of 

 mercury from the cistern by making it portable or otherwise after it 

 is adjusted, can no longer be correct, or give the height of the column. 



" To obviate these inconveniences, I have substituted a cistern of 

 iron in place dfth'j wooden one ; it is fastened to the tube by a thick 

 collar of wood, which is glued on in the usual manner ; a screw passes 

 through the centre of the bottom, so as to move in a line with the ba- 

 rometer tube ; it is terminated inside the cistern by a piece of cork tied 

 over with leather, so that the instrument being inclined that the tube 

 may be filled with mercury, this cork may be screwed up against the 

 end of the tube, and effectually preserve the metal within from oscilla- 

 tion, without subjecting the cistern itself to any pressure. 



" As there is no pressure on the mercury in the cistern, the wooden 

 cap may be left so porous in one part, as to allow of the ready access 

 of air, so that the column shall fall freely to its proper level, without 

 any danger of losing mercury. 



" Another great object in a mountain barometer, is to obtain the 

 temperature of the mercury, which is done by fixing a thermometer 



