We now describe the English weights and measures as they stood on the last day of the year 1825, immediately before the introduction by law of the imperial measures, with some remarks on their states at different times. As it is not to such an article as the present that the young arithmetician will refer, it will not be necessary to give more than a condensed set of tables. For the modern continental measures which follow, we have to acknowledge great assistance from Dr. Kelly's Cambist,' the standard work on the subject.
Troy Weight.—This weight is said to have always been the standard weight of the country : on this assertion we have some doubts ; but this is not the place to enter on them at length. The pound is 12 ounces; the ounce is 20 pennyweights ; the pennyweight is 24 grains. The pound is 5760 grains. There is but one grain in use, whether troy or averdupois, and a cubic inch of pure water is grains (baro meter 30 inches, thermometer 62* Fahr.). A cubic foot of water is 751374 pounds troy. Wheat and bread were once measured by this weight, but latterly only gold and silver. It is usual to say that pre cious stones are also measured by troy weight ; but, as may be supposed, the measure of these is the grain. The diamond is measured by carats of I5li to the ounce troy ; so that the carat is 3,1 grains, very nearly. In pearls, the old foil measure already noticed still exists ; for the pearl grain is one-fifth less than the troy grain. In the 17th century the goldsmiths divided the ounce troy into 24 carats of four grains each for gold and silver : so that the pound troy contained 1152 gold-carat grains. They also divided the ounce into 150 carats of four grains each, for diamonds : so the pound troy contained 7200 diamond carat grains. But now the CARAT has only the sense noted under that word, for gold and silver ; and is altered as above for diamonds.
According to the old statutes, the pound troy is 7680 grains ; for 32 grains are to make a pennyweight, 20 pennyweights an ounce, 12 ounces a pound. It is not known when or why the pennyweight was first+ made 24 grains. In some old books a grain is 20 mites, a mite 24 droites, a droite 20 peroites, and a peroite 24 blanks. This division of the grain into 230,400 parts must of course have been book-learning: it is said to have been confined to the moneyers.
In Swallow's Almanac for 1673, we find the troy weight given as for " pearls, precious stones, gold, silver, bread, and all manner of corn and grain ; and this weight the apothecaries ought to use."
Apothecaries' Weight.—In dispensing medicines, the pound troy (Does that weight ever occur in prescriptions ?) is divided into 12 ounces, the ounce into 8 drams, the dram into 3 scruples ; consequently each scruple is 20 grains. But in buying and selling medicines wholesale, averdupois weight is and always has been used. The Pathway,' so often cited (1596), says, "all physical! drugges" were weighed by aver dupois, and Jeake (1674) says that "many ' (only many) of the "physical doses" are weighed by what we now call apothecaries' weight. The fact seems to be that in the first instance the more precious drugs, as musk, were weighed by troy weight, in the same manner as the more precious metals ; and that the common medicines were dispensed by fractions of what was then the common pound, as we shall see under the next head.
Apothecaries' fluid 1836, in the new edition of the Pharma.copccia; the College of Physicians prescribed the use of the following measure :-60 minims make a fluid dram ; 8 fluid drama a fluid ounce ; 20 fluid ounces a pint. For water this is actual weight as well as measure, since the imperial pint is 20 ounces averdupois of water ; but for other liquids the fluid ounce § must merely be con sidered as a name given to the 20th part of a pint. The minim of water is as nearly as possible the natural drop ; but not of other sub stances, the drops of which vary with their several tenacities.
According to Dr. Young (who has reduced them from Vega), the apothecaries' grains used in different countries are as follows :—I000 English grains make 1125 Austrian, 956 Bernese, 981 French, 850 Genoese, 958 German, 978 Hanoverian, 989 Dutch, 860 Neapolitan, Piedmontese, Portuguese, 909 Roman, 925 Spanish, 955 Swedish, 809 Venetian.
The recent alterations in the government of the medical profession have produced proposals to alter the method of weighing medicines. A committee of the General Council of 3lcdical Education has given a recommendation to the following effect. The pound averdupois is to have its ounce divided into drachms, scruples, and grains, as in the present troy ounce. To effect this, a new grain is invented, being of the present grain : and the pound is to be 76S0 grains, as of :dd. What purpose this change can answer, or, supposing a purpose, now it can bring benefit enough to counterbalance the alteration of the grain in which all doses are now remembered, and all prescriptions written, we cannot imagine.