284

Hydrostatics.

to the last Degree of Accuracy ; especiallyin the New Structure and Method of usingit, as represented in Plate XV. Fig. 4.The Parts of which are as follow; A B,the Foot on which it stands; C D, a Pil-lar supporting a moveable Brass Plate EF,fastened thereto by the Screw in the Knobe. In the End of this Plate is fix’d an up-right Piece IK, supporting another PlateGH, which Hides backwards and forwardsthereon, and is moveable every way aboutit. In the End of this Plate, at H, isfix’d (by a Nut beneath) a Wire L M,tap’d with a fine Thread from one End tothe other; upon this moves the Swan-NeckSlip of Brass N O, to which a very exactBalance is hung at the Point N; to one ofwhose Scales P is appended the heavy Bo-dy R, by a fine Horse-hair or Piece of SilkS : The Weight of the said Body R in theAir is express’d by the Weights put intothe Scale Q^_to make an Equilibrium there-with, which being destroy’d by immergingthe Solid in the Fluid TV, contain’d inthe Glass WV, is again restor’d by Weightsput into the Scale P. So that the Weightsin the Scale (fcompared with those in the Scale

P, Jhew

Bulks, and consequently specific Gravities, in equal'Weights of Spirits, to the 30, 40, or 50 thousandthPart of the Whole, which is a Degree of Accuracy,beyond which nothing can be deiir’d.