304 Old-time Schools and School-books
I have mentioned the Rule of Three. It was recognized as an arithmetical landmark and I give Pike's definition: —
The Rule of Three teacheth, by having three numbers given, to find a fourth, that fhall have the fame proportion to the third, as the fecond to the firft.
This is sufficiently clear; but some of the book's explanations are quite unintelligible to the present generation, as for instance: —
When tare, and tret and cloff are allowed.
Deduct the tare and tret, and divide the futtle by 168, and the quotient will be the clofF, which fubtract from the futtle, and the remainder will be the neat.
One fails to make any sense out of such a jumble until he reads the definitions appended to it.
Tare is an allowance, made to the buyer, for the weight of the box, barrel, or bag which contains the goods bought.
Tret is an allowance of 4 ft) in every 104 ft) for wafte, duft, &c.
Cloff is an allowance of 2ft) upon every 3 cwt.
Suttle is, when part of the allowance is deducted.
Neat weight is what remains after all allowances are made.
Another rule that has an equally unfamiliar sound to modern ears is this : —
To find the Gregorian Epact.
Subtract 11 from the Julian Epact: If the fubtraction cannot be made, add 30 to the Julian Epact; then fubtract,