560 Sir george shuckburgh’s Qbfervations 
Feet. 
The bottle empty or exhaufted till the gage Hood at 29 15 inches] 
weighed (determined from four different tnals, and the balance 1 2657.40 
turning with tV of a grain) — — — J 
Increafe of weight when filled with air, from four trials certain 
But the bottle was exhaulted only in the proportion 
of 29.15 inches to 29,27 inches; therefore if a perfect 
vacuum could have been made, the difference of weight 
would have been 1 6.22 grains inftead of 16.1 3 grains. 
Again, the water was colder than the air by 2 0 ; the one 
being 53 0 , and the other only 5 t 0 : now water, from 
former experiments, I find to expand about — 0 |^ with 
2 0 of heat; therefore, if the water had been of the fame 
temperature with the air that was examined, the weight of 
an equal volume would have been only 13558,5 grains ; 
and laftly, 13358.5 divided by 16.22 gives 836^, and 
by fo much is water heavier than air in thefe circum- 
ftances. 
(y) hawkesbee’s experiments made the air 850 lighter than water, the baro- 
meter being at 29 7 , and Dr t halley iuppoiei ii about S.oo. lVir. caven- 
dish, in weighing 50 grains of a r, when the barometer was at 29}, and the 
thermometer at 50% concluded the fpeciiic gravity of air to be about 800 alfo. 
Now my experiment, reduced to the fame eircumftances with his, would give 
817 for this gravity, no great difference in an affair oi inch delicacy. 
to do of a grain — — 
Bottle filled with water, whole heat was 5 1 
Weight of the water, exclufive of the b ttle, 
16220.00 
13562.60 
By 
