Hydrostatics.

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Ounces contained in a cubic Foot of eachrespective Sort of Matter therein mention’d.Therefore, if the Magnitude of any Body bemultiplied by the specific Gravity , the Pro-du£i will be its absolute Weight. Thus, sup-pose I would know what Weight of Leadwill cover a Church whose Area is 30000Feet, and the Thickness of the Lead T 4- B 'of a Foot: Then per Rule, (30000 x-rir —)300X11325 — 339750 Ounces, or 97^Tons ; the Weight required.

Another useful Problem is, to find the-Magnitude of any Thing , when the Weightis known ; which is done by dividing theWeight by the specific Gravity in the. Table ^the Quotient is the Magnitude fought. ForInstance, What is the Magnitude of seve-ral Fragments of Coral whose Weight is 7Ounces ? Divide 7 by the specific Gravity269©, the Quotient is -nAA-s- of a cubicFoot: then t-etVW X 1728 = As cubicInches, very nearly the Magnitude re-quired.

Also, by knowing the Magnitude andWeight , we can find the specific Gravity, bydividing the Weight by the Magnitude in cubicBeet. Thus suppose a Piece of Marble con-tain 4 cubic Feet, and weighs 603 Ib. or10800 Ounces; then — 2700, the

specific Gravity required, as per Table.

Having