Page 163 - The Wellington photographic handbook

In this book the quantities given in the metric system are
not the equivalents of the corresponding quantities in the British
system. The proportions are approximately the same, but the
quantities have been arranged so that the bulk shall be the most
convenient in each system.
Water is given in fluid ounces.

BRITISH MEASURES.
APOTHECARIES' WEIGHT.
(By which formulae are made up.)
20 grains =1 scruple.
3 scruples — 1 drachm = 60 grains.
8 drachms =1 ounce =480
AVOIRDUPOIS WEIGHT.
(By which chemicals are sold).
437$ grains = 1 ounce.
16 ounces = 1 pound =7000 grains.
J ounce =109 grains (approx.) ; \ ounce =219 grains (approx.)
| ounce =328 grains (approx.).
FLUID MEASURE.
60 minims =1 drachm.
8 drachms =1 ounce =480 minims.
20 ounces =1 pint (in U.S.A. 16 ozs. = 1 pint).
2 pints =1 quart = 40 ounces.
4 quarts =1 gallon =160 ounces.

THE METRIC SYSTEM.

There are three principal units, namely, the metre, the litre
and the gramme, the units of length, capacity and weight respec-
tively. Multiples of these units are obtained by prefixing to the
names of the principal units the Greek words deca (10), hecto
(100), and kilo (1,000) ; the sub-multiples or divisions are obtained
by prefixing the Latin words deci centi (T^ 0 ), and milli
1 These prefixes form the key to the whole system.
(jjy ^).
LINEAR MEASURE.
10 millimetres =1 centimetre = -3937 inches.
10 centimetres =1 decimetre = 3-937 inches
10 decimetres =1 metre = 3-281 feet.
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