Egypt....Gold... Pound (100 pi- 4.9431 The actual standard is the British pound

(a) The exchange rates shown under this heading are recent quotations and given as an indication of the values of currencies which are fluctuating in their relation to the legal standard. They are not to take the place of the Consular certificate where it is available. (b) And silver.

VALUE OF FOREIGN COINS IN UNITED STATES MONEY-(Cont.)

(a) The exchange rates shown under this heading are recent quotations and given as an indication of the values of currencies which are fluctuating in their relation to the legal standard. They are not to take the place of the Consular certificate where it is available. (b) And silver.

time is divided into 24 hours continuously beginning at 1 P. M. and not into two periods of 12 hours each. Let there be two clocks, one regulated for mean solar time, indicating 24 hours from meridian to meridian of a fixed star; the latter clock will indicate only 23 hr., 56 min., 4 sec., of mean solar time; the fixed star passing the meridian 3 min., 56 sec., earlier every day.

A sidereal year is the time which elapses during a complete revolution of the earth around the sun, measured by the recurrence of the same fixed star selected at the beginning of the observation; it is 365 days, 6 hrs., 9 min., 9.3145 sec. of mean solar time.

NUMBER OF DAYS BETWEEN ANY TWO DAYS WITHIN TWO YEARS

EXAMPLE.-The number of days from October 18 to the following June 9

= 525 291 = 234 days. Method: beginning with the later date in left-hand column, 9 day, trace across table the June in second year, finding 525; then from 18 day in left-hand column trace across table to October in first year finding 291, subtracting this number from the former

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234 days.

EXAMPLE. To find the date upon which a note given March 11 for 45 days will become due: Find 11 day in left-hand column; trace across table to March finding 70. Then 70+45 = 115. Find 115 in the table, observe the month at the top of column (April), then trace to the left-hand column finding 25. The date is April 25. NOTE.-The above table applies to ordinary years of 365 days. For leap-year add one day to each number of days after February 28.

Longitude. The time required to make one complete revolution of the earth from meridian to meridian is not only divided into 24 hours, but it is also divided into 360 degrees. As the 24 hours and 360° are invariable, they bear a constant relation to each other; for example, 360 ÷ 24 15° of the great circle in one hour. Further,

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15 X 60 15 X 60 = 15" of 60 60 the great circle in 15 seconds of time. The east and west D.°, M.', S.", of the great circle are called degrees, minutes, and seconds of longitude. The hour, with its subdivisions of minutes and seconds, is reckoned as time.

15′ of the great circle in 15 minutes of time, and lastly

Longitude is reckoned along the equator from the first meridian. There is no natural starting-point for longitude as there is for latitude; the latter is reckoned from both sides of the equator to the north and south poles respectively. A quadrant of the earth's surface, or the distance from the equator to the pole, is divided into 90°, and again into minutes and seconds, and decimals of a second-of latitude.

Longitude must have an agreed starting-point; seafaring men have agreed upon, and commonly reckon, longitude east or west from Greenwich, England. Any other place would answer equally well, such as the longitude of Paris, or of Washington, but varying longitudes would result in endless confusion in the use of nautical tables, coast survey charts, etc.

A navigator's chief reliance is in the accuracy of the ship's chronometer as a timepiece which must correctly indicate Greenwich time, by which is meant that his chronometer must point to 12 o'clock when the sun is on the Greenwich meridian. Chronometers, like other trains of mechanism, are subject to variation, and the rate, whether fast or slow, must be carefully noted when computing daily observations. Suppose a ship going westward from Europe, and the noon observation to show a variation of 3 h., 36' slower than the chronometer or Greenwich time, the position of the ship would be 54° west of Greenwich or within 20° of New York, for the difference in time between the two meridians is the difference in longitude.

METRIC SYSTEM OF WEIGHTS AND MEASURES

Bureau of Standards

Fundamental Equivalents. The fundamental unit of the metric system is the meter-the unit of length. From this the units of capacity (liter) and of weight (gram) were derived. All other units are the decimal subdivisions or multiples of these. These three units are simply related, e.g., for all practical purposes one cubic decimeter equals one liter, and one liter of water weighs one kilogram. The metric tables are formed by combining the words "meter,' gram," and " liter" with six numerical prefixes as in the following tables:

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All lengths, areas, and cubic measures in the following tables are derived from the international meter, the legal equivalent being 1 meter 39.37 inches (law of July 28, 1866). In 1893 the United States Office of Standard Weights and Measures was authorized to derive the yard from the meter, using for the purpose the relation legal3,600 ized in 1866, 1 yard equals 3,937

meter. The customary weights are likewise referred

to the kilogram (Executive order approved April 5, 1893). This action fixed the values, inasmuch as the reference standards are as perfect and unalterable as it is possible for human skill to make them.

All capacities are based on the practical equivalent 1 cubic decimeter equals 1 liter. The decimeter is equal to 3.937 inches, in accordance with the legal equivalent of the meter given above. The gallon referred to in the tables is the United States gallon, 231 cubic inches. The bushel is the United States bushel of 2,150.42 cubic inches. These units must not be confused with the British units of the same name, which differ from those used in the United States. The British gallon is approximately 20 per cent larger and the British bushel 3 per cent larger than the corresponding units used in this country.

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The customary weights derived from the international kilogram are based on the value 1 avoirdupois pound 453.5924277 grams. This value is carried out further than that given in the law, but it is in accord with the latter as far as it is there given. The value of the troy pound is based upon the relations just mentioned, and also the 5,760 7,000

equivalent

avoirdupois pound equals 1 troy pound..