molished it in the late war. It was 31 feet in length, and 21 in diameter, and pretty nearly cylindrical. Pray how many tons of wine would the same contain?

LXXVII. SPECIFIC GRAVITY OF METALS.

THE specific gravity of a body is the relation that the weight of a body of one kind hath to the weight of an equal magnitude of a body of another kind; the knowledge of which is of great use in computing the weights of such bodies as are too unwieldy to have their weight discovered by other

means.

The following TABLE shows the specific gravity, to rainwater, of metals, and other bodies; and the weight of a cubic inch of each, in parts of a pound avoirdupois, and in ounces troy, and parts of an ounce.

Sp. Grav.wt. lb. Avoir. | wt. oz. Troy.

BODIES.

Common glass

Case 1. The linear dimensions, or solidity of any body be

ing given, to find its weight.

RULE.

Multiply the cubic inches contained in that body by the tabular weight corresponding; the product will give the weight, in pounds avoirdupois, or ounces troy.

EXAMPLES.

(1) What is the weight of a piece of oak of a rectangular form, whose solidity is 12096 cubic inches?

(2) What is the weight of a piece of fir, whose girt is 20 inches, and length 40 feet?

(3) What is the weight of an iron shot, of 7 inches diameter?

(4) What is the diameter of an iron shot, weighing 42 lb.

avoirdupois?

(5) What is the weight of an iron bamb of 3 inches thick, the greatest diameter being 16 inches?

(6) Required the weight of one of the Portland key-stones to the middle arch of Westminster Bridge, the diameter of the arch being 76 feet, the height of the key-stone 5 feet, the chord of its greatest breadth, to the front of the arch, 3 feet 4 inches, and its depth of the arch 4 feet.

(7) In the walls of Balbee, in Turkey, there are three stones, laid end to end, now in sight, that measure in length 61 yards; one of which in particular is 63 feet long, 12 feet thick, and yard over: Now if this block was marble, what power would balance it, so as to prepare it for moving?

Case 2. The weight of any body being given, to find the solidity and the specific gravity thereof,

RULE.

Divide the given weight by the tabular weight corresponding to the name of the same kind, and the quotient will be the solidity in cubic inches,

EXAMPLES,

(8) What will a block of marble, weighing 8 tons 14 cwt. come to, at 6s, per foot solid?

(9) Suppose that a man of war, with all its ordnance, rigging, and appointments, draws so much water as to displace 1300 tons of sea water, London beer measure. The weight of the vessel is required.

(10) What will a chain of standard gold weigh in water that raises a fluid an inch, in a vessel 3 inches square, when put into it; and supposing the workman had

adulterated the said chain with 142 ounces of silver, how much higher would the water, upon its immersion, be raised in the vessel?

(11) Hiero, king of Sicily, ordered his jeweller to make him a crown containing 63 ounces of gold; the workman thought of substituting part silver therein, to have a proper perquisite: which taking air, Archimedes was appointed to examine it; who, on putting it into a vessel of water, found it raised the fluid, or that itself contained 8,2245 cubic inches of metal; and having discovered that the cubic inch of gold more critically weighed 10,36 ounces, and that of silver but 5,85 ounces, he, by calculation, found what part of his majesty's gold had been changed; and you are desired to repeat the process.

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PART V.

LXXVIII. CHRONOLOGY

Is the art of estimating and comparing together the times when any memorable transaction hath happened, such as related in history, whether civil or ecclesiastical.

It also takes a view of the various fasti, calendars, and methods of computing time, practised by different nations, compares them together, and settles such order and harmony among them, that the exact time in which any remarkable event happened may be certainly known.

The Mohammedans from the flight of

Mohammed, called the Hegira