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L V. Description of a New portable Mercurial Barometer. 



By J. A. Calantarients. 

 To the Editors of the Philosophical Magazine and Journal. 



19 Guildford Street, Russell Square, W.C., 

 Gentlemen, April 20, 1870. 



I BEG to enclose two drawings, with a description, of a new 

 portable mercurial barometer which I have invented, and 

 hope you will do me the favour of inserting it in the next Num- 

 ber of your Magazine. 



I beg to enclose also the copy of a letter from Dr. Balfour 

 Stewart, of Kew Observatory, addressed to the makers, together 

 with the account of the comparison mentioned in that letter. 



The slight discrepancy between the indications of my baro- 

 meter and that of the standard is entirely owing to the careless- 

 ness of the makers, or rather of the man who tested and made 

 the scale; for there is no reason whatever, as you will see from 

 the principle on which it is constructed, why it should not be 

 made as accurate as a standard one. The present scale, how- 

 ever, is correct. 



Besides fulfilling the ordinary requirements of a barometer, 

 it is, I believe, well adapted for taking mountain-measurements, 

 as it is light, of small size, and compact form. Instead of mer- 

 cury other fluids can, of course, be made use of, if thought pre- 

 ferable. I very much regret that professional duties have so long 

 hindered me from taking the necessary steps for its publication. 

 I invented it whilst a student of medicine at University College. 

 I remain, 



Your obedient Servant, 



J. A. Calantarients. 



Kew Observatory, Richmond, Surrey, S.W., 

 January 14, 1869. 



Gentlemen, — I enclose an account of our comparison of Mr. 

 Calantarients' s barometer with our standard. The result is a fair 

 one, and the instrument seems to be well compensated. 



Yours truly, 



Messrs. Newcombe and Co. B. Stewart. 



Comparison of Calantarients' s Barometer with the Standard Ba- 

 rometer of the Kew Observatory. 

 inches. 



30= -0-19 

 29= -0-45 

 28=-0-51 



Mean correction at 



temperature remaining 

 constant. 



26=-0-36j 



2 B2 



