300

Hydrostatics.

very exaBly 1000 Ounces Averdupois, or 62Pounds and a half ; which may be reduced

to

Weight is desired to the hundredth Part of a Grain, itmay easily be had by proceeding in the following Man-ner. Let the Body to be weighed be placed in theScale d, and put the Weights in the Scale* ; and let thesebe so determined, that one Grain more shall be toomuch, and one Grain less too little. Then the Ba-lance being gently moved up or down by the Screw P,till the Equilibrium be nicely shewn at 0 ; and then ifthe Index T be at the middle Point (a) of the Wirerr,it shews the Weights put into the Scale e are just equalto the Weight of the Body.

32. But if the Index T stand at any Part between aand r, it shews the Number of Grains in the Scale*were more than equal to the Weight of the Body in theScaled, because the Wire pn is now made lighter byfinking below the middle Point. Thus, suppose theWeights put into the Scale e were 1095 Grains, andthe Index T cuts the 36th Division above a, it Ihewsthat 36th hundredth Parts of a Grain arc to be added, orthat the Weight of the Body is 1095,36 Grains.

33. On the other Hand, had the Index stood at 36,the Division below a, it would have shewn the Weightsin the Scale e were more than equal to the Weight ofthe Body by 36 Hundredths of a Grain ; and that therethe Weight of the Body was 1094,64 Grains. By thisMethod we find the absolute Weight of the Body; therelative Weight is found by weighing it hydrostaticallyin Water as follows.

34. Instead of putting the Body in the Scale d, asbefore, let it be appended with the Weight F at theHook c, by a Horse-hair as at R, supposing the Vesselof Water O were away; then the Equilibrium beingmade, the Index T standing between a and r, atthe 36th Division, Ihews the Weight of the Body1095,36 Grains. As it thus hangs, let it be immersedin the Water of the Vessel O, and it will become lighterby much ; the Scale e will descend till the Beam of the

Balance