L J^^ i 



generally very </ri', the raiefadlion produced, as fhewn by the 

 pear-gage, was, five times, between 3000 and 4000, the mere 

 in the barom'"-gage (landing at the fame times always above 

 -^-th pare of an inch higher than it flood in a flandard ba- 

 rom"" of a wider bore, which was filled with mere'' made very 

 hot, as was alfo the tube *, as well as I could fill it without 

 boiling the merc^ in the tube ; and the mere' in the reduced 

 bar oni"'- gage, funk below the level of the furrounding merer. 

 In the other nine trials, the rarefadlion as fhewn by the pear- 

 gage was from 9000 to 26000 ; v/hen the mere' in the barom""- 

 gage flood at rili-j'^hs of an inch higher than that in the flan- 

 dard barom'^, and funk in the reduced barom"" ftill lower than 

 before beneath the flagnant mere'. In feveral trials made from^ 

 the 15th of September following to the 5th of December, 

 when the air was always moiji, I could not raife the meTc' 

 in the baromr-gage to the height of that in the flandard ba- 

 rom'' (which flood clofe befide and parallel to it in the fame 

 cifiern) except once, and never fo high even in the pear-gage 

 as it flood in mofl: of the former trials : whence it is evi- 

 dent, from the correfpondence between the three gages, that 

 a moifl atmofphere prevents the exhaviflion, not only of aque- 

 ous 



* The tube was placed in a heattd gun-barrel, and filled with the mercy heated on 

 fand , when filled, it was taken out of the gun-barrel, and being fo cold, as juft not 

 to burn my gloves, an air-bubble was moved through it ; and the mercy, as I found 



by trials, iiood hi;jher tinn it ever would do if poured cold intn the fame tube. 



