Hydrostatics

325

46. The Diameter of this Globe was 5,3—D, andit weieh’J 137,5 ' n Air. A Globe of Air of the fameDiameter weighs 23 Grains, very nearly; therefore1 37>5~f" 2 3 — 160,5 Grains, the Weight of the Globe inVacuo. Wherefore, as 23 : 160,5 : : y D : 2S =98,626. Again, as 160,5 : *37,5 ; : lYZl : 165,628—Inehes the Bladder would fall in the Air in one Se-cond. But with the fame relative Weight 137,, itwill in Vacuo descend thro' the Space 5=49,313 in theTime o',5456 = T, and acquire the greatest Velocitywith which it can descend in Air. The Time of theFall was 181", in which with that Velocity the Globewould describe 278 Feet 8 Inches by an uniform Mo-tion ; for0^,5456 : 98,626 Inches : : 185" : 278' Feet.Lastly, subduct 1,3863 S — c 2 Feet, and there remains273 Feet, though in the Table, by a more accurateCalculation, it is but 272 Feet, 7 Inches, and by theExperiment it was 272 Feet.

47. The following Table shews, in the first Co-lumn, the Weight of each Globe or Bladder ; the se-cond its Diameter ; the third the Time in which theyseverally descended through the Height of 272 Feet;the fourth shews the Spaces they sho dd have descendedthrough by the Theory ; and the last Column strewsthe Difference between the Theory and Experiments.

The sp eightin Grains,

Diameterin Incbe:,

7 imes ofhe Fall

Spaces perfheory .

Difference.

128

5,28

'9"

Feet. Inch.271 — n

Feet. Inch.

0 — 1

>56

5 > ! 9

- 17

*3

1

0 — of '

137s

5>3

.8|

272 — 7

0 — 7

97 1

5,26

22

277 — 4

5 — 4

99 r

5

21

282 — O

10 —

48. According to this Theory, having found the Re-sistance which a Globe meets with in descending in anyresisting Medium, agreeing to its greatest Velocity, it iseasy then to find its Resistance for any lesser Velocityproposed ; because the Resistance for any given Veloci-ties, will be as the Squares of those Velocities, -

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