AnalyfnoftheAk. tll 



ftrongeft bombs or cannon, and whirl fortifi- 

 cations in the air. 



This fort of mercurial gage, made ufe of 

 in Experiment 89, with fomeunduous mat- 

 ter, as Treacle, or the like tinged liquor 

 on the Mercury in the tube, to note how 

 high it riles there, might probably be of fer- 

 vice, in finding out unfathomable depths of 

 the fea, viz by fixing this fea-gage to fome 

 buoyant body, which mould be funk by a 

 we.ght fix'd to it, which weight might by 

 an eafy contrivance be detached from the 

 buoyant body, as foon as it touched the bot- 

 tom of the fea , fo that the buoyant body 

 and gage would immediately afcend to the 

 furface of the water. The buoyant body ought 

 to be pretty larg,, and much lighter than the 

 water, that by its greater eminence above the 

 water it might the better be feen : for 'tis 

 probable that from great depths it may rife 

 at a confutable diflance from the mip tho- 

 rn a calm. r ' 



For greater accuracy it will be needful, 

 m, to try this fea-gage, at feveral differen 

 depths down to the greatefi depth that a 

 >ne will reach, thereby to difcover, whe ! 

 Act or how much the fpring of the air is 

 difturbcd or condenfej, not only by the great 



P 2 prefiure 



