VOL. XXXIII.] PHILOSOPHICAL TRANSACTIONS. SQ 



A Barometrical Experiment; by M. Jnd. Celsius. N° 388, p. 313. Tran 

 slated from the Latin. 



For observing the variation of the column of mercury in the barometer, 

 according to different heights in the atinosphere, the deep mines in Swedlen 

 may be reckoned peculiarly adapted. For not only their depth may be mea- 

 sured with great accuracy, but also the whole observation performed in a short 

 time : an advantage often wanting in making the like experiments on high 

 mountains. If therefore a great many experiments were made in different 

 mines, no doubt but the true progression, by which the density of the air 

 decreases, would at length be discovered. 



Aug. 28, 1724, M. Celsius made the following experiment in the Salan silver 

 mine, about 7 miles to the west of Upsal. At the entry to the queen Chris- 

 tina's shaft, he observed the height of the mercury at 30.38 inches, or the 

 4-f§-§- of a Swedish foot; he was then let down with the barometer in a vessel 

 by a rope, to the depth of dsS feet, where he observed the mercury ascend to 

 30.98 inches : from thence being drawn up again to the mouth of the shaft, 

 he observed the column of mercury at the same height as before, viz. 30.38 

 inches. So that the mercury raised to the height of 630 feet in the air, falls 6 

 lines or , f „ parts of a foot ; and consequently, if the air were supposed of 

 equal density every where, the variation of one line in the column of mercury 

 would answer to ]06 feet perpendicular height. During the time of the ob- 

 servation, there was a little rain and wind; yet no sensible alteration could be 

 observed at the same time in the column of mercury in another barometer, 

 fixed to a wall above the mine. 



Next day, the sky being serene and calm, the mercury stood at 30.36 inches 

 at the foot of the church of Sale, not far from the mine; but going up 145 

 feet high in the tower of the said church, he found the mercury at 30.23 inches: 

 so that the height of 111 feet and -^ parts answers to the descent of one line 

 in the barometer. 



That this observation may be duly compared with the experiments of this 

 kind, made by others, it is to be noted, that the ratio between the Swedish 

 and Paris foot royal is nearly that of 1000 to IO96, or 125 to 137, as Mr. 

 Celsius accurately observed by comparing them together. 



Remarks on the Observations made on a Chronological Index of Sir Isaac 



Newton, translated into French by the Observator, and published at Paris. 



By Sir Isaac Neivton. N° 389, p. 315. 



Nov. 11, 1725, a small tract in print was delivered to me, as a present, 

 from Mr. Wm. Cavelier, jun. a bookseller at Paris, a person unknown to me, 



VOL. vii. N 



