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CHAPTER VI.

WEIGHTS AND MEASURES.

HOW TO READ A GAS METER.

The dial marked "1 THOUSAND" in the accompanying illustration is divided into hundreds; the dial marked "10 "THOUSAND" is divided into thousands; that marked "100 THOUSAND" into ten-thousands, and that marked "1 MILLION" into hundred-thousands. When 1,000 cubic feet of gas have been consumed, the pointer on the dial marked "1 THOUSAND" will have made a complete rotation and the fact will be indicated by the pointer of the next dial at the left, which will point to the figure 1. When 10,000 cubic feet of gas have been consumed, the pointer on the "10 THOUSAND dial will point to 1, and so on. In reading a gas meter, put down the hundreds first, then the thousands, and so on, always counting the figure just under, or

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CUBIC

1. MILLION

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100.

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which has just been passed by, the pointer. In the illustration about half a hundred is indicated on the "1 THOUSAND" dial, three thousands is indicated on the next dial, two tenthousands on the next dial, and one one-hundred-thousands on the "1 MILLION" dial. The reading will be 123,050. The dial marked "TEN TEET" is called the units dial. It is used for testing the meter to discover whether it is in working order or not. Each mark represents a cubic foot and the com-. plete circle 10 cubic feet. If the pointer moves when no gas is burning, it indicates a leak. If it does not move when the gas is burning, or if its motion is unsteady, it indicates a derangement in the mechanism and shows that the meter requires attention.

TEN

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GAS METER INDICATOR DIALS.

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knot a speed of 1 nautical mile per hour

In the United States the nautical mile is defined to be one sixtieth part of the length of a degree of a great circle of a sphere whose surface is equal in area to the area of the surface of the earth. In France, Germany and Austria the nautical mile has a length of 6,076.23 feet. In England the nautical mile is 6,080 feet.

Miles at sea are understood to be nautical miles. Therefore it is no more necessary to say "nautical miles when speaking of a sea distance than to say "statute" miles when speaking of a land distance.

Landsmen are apt to confuse knots with nautical miles. A knot is not a measure of distance but a measure of speed, and the only measure of speed in the English language. When speaking of a vessel that travels, say 20 knots, we mean that the vessel is traveling at a speed of 20 nautical miles per hour; but the distance covered may be one nautical mile or a thousand, depending upon the length of time during which the 20-knot speed is maintained. Only landsmen use the expression "knots per hour." The "per hour" is superfluous and incorrect.

Following is a list of the lighthouses from Bremerhaven to Dover; figures expressed in sea miles. There is no table in existence which exactly corresponds with the excellent tables which we give from Fastnet Light to Flushing.

PERPETUAL CALENDAR.

To find the day of the week for any given date.

1. Take the last two figures of the year, add 4 of them (neglecting remainder). Thus: 194949+12=61.

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DECIMAL SYSTEM-WEIGHTS AND MEASURES.

A meter is one ten-millionth of the distance from the equator to the North Pole.

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The metric system, formed on the meter as the unit of length, has four other leading units, all connected with and dependent upon this. The are, the unit of surface, is the square of ten meters. The liter, the unit of capacity, is the cube of a tenth part of the meter. The stere, the unit of solidity, has the capacity of a cubic meter. The gram, the unit of weight, is the weight of that quantity of distilled water at its maximum density which fills the cube of a hundredth part of the meter. Each unit has its decimal multiple and submultiple, that is, weights and measures ten times larger or ten times smaller than the principal unit. The prefixes denoting the multiples are derived from the Greek, and are deca, ten; hecto, hundred; kilo, thousand; and myria, ten thousand. Those denoting sub-multiples are taken from the Latin, and are deci, ten; centi, hundred; milli, thousand.

10,000.

1,000.

100.

10.

Unit.

0.1. 0.01. 0.001.

Length.

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