Very respectfully, your obedient servant,
Geo. F. Dunning.
Rev. Daniel B. Woods, Philadelphia.
P.S.—The following rules for making calculations of weight and value may not be unacceptable to the readers of your book.
1. To convert Pounds Avoirdupois to Ounces Troy.—From the avoirdupois weight, expressed in pounds and decimals of a pound, subtract one eighth. Divide the sum thus obtained by ·06, and the quotient will be the Troy weight in ounces and decimals.
2. To convert Ounces Troy to Pounds Avoirdupois.—Multiply the Troy weight in ounces and decimals by ·06. To this product add its seventh, and you have the avoirdupois weight in pounds and decimals.
3. To find the Standard Weight of Gold or Silver, the gross weight and fineness being given.—Multiply the gross weight, in Troy ounces and decimals, by the fineness in thousandths, and divide the sum by 900. The quotient will be the standard weight in ounces and decimals.
4. To find the Value of Gold and Silver.—Gold. Multiply the standard weight, in Troy ounces and decimals, by 800, and divide the product by 43. The quotient is the value in dollars and cents.
Silver. To the standard weight, in Troy ounces and decimals, add its one eleventh part, and eight tenths of one eleventh. The sum will be the value in dollars and cents.
5. To convert the fineness expressed in Carats into Thousandths.—Multiply the carats by 41⅔. The product is the equivalent fineness in thousandths.