the Calendar. This Bill enacted that the new year should begin on the 1st of January, instead of the 25th March, and that 11 days, intermediate between the 2nd and 14th of September, 1752, should be omitted.

In works of that period, and prior to it, a double date is often met with for the months of January, February, March, up to the 24th March; as for instance the "15th February, 1754-5." In such cases the former date indicates the year ac-cording to the old style, and the latter year according to the new style.

Rule to Find Leap-year.

When the figures denoting the year, or in exact centuries when the figures denoting the hundreds in the date, can be evenly divided by 4, the year is leap-year; when there is a remainder, it denotes the number of years that have elapsed since leap year. Thus, 1860 is divisible by 4 without remainder, it was therefore leap-year; but 1863, on division by 4, gives a remainder of 3, thus showing that the year 1863 is the third after leap year. Again, 1600 and 2000 complete each an exact century, and the numbers 16 and 20, which denote the hundreds in the dates are each divisible by 4, hence the years 1600 and 2000 are leap years; but in 1700, 1800, and, 1900, the number 17, 18, and 19 are not so divisible, and, therefore the years are not leap years.

THE CHANNEL ISLANDS,

VIZ.,

GUERNSEY, JERSEY, ALDERNEY, AND SARK.

The weights and measures are the same as those of the United Kingdom of Great Britain and Ireland.

FRANCE.

The Decimal or Metric system of weights and measures is now very generally used in many countries throughout the world. France took the initiative in introducing this system into Europe.

In 1790 Louis XVI., in accordance with a Resolution passed by the Constituent Assembly, invited the nations of Europe, and among them England in particular, to co-operate with him in fixing a universal and natural basis for an international system of weights and measures; but the invitation was not accepted, and ultimately the French Academy proceeded by themselves. The question of money, weights, and measures was referred to some of the ablest men of the age, and the Metrical or Decimal system was the result.

Delambre and Mechain calculated, from measuring an arc of the meridian between Dunkirk and Barcelona, the length of the quadrant of a meridian from the Equator to the Pole, and took the ten millionth part of that meridian as the unit of length, calling it a Metre. They fixed the square of 10 Metres as the unit of surface measure, calling it an Are; the cube of the tenth part of the Metre as the unit of measures of capacity, calling it a Litre; and the cube of a Metre as the unit of solid measure, calling it a Stere. As the unit of weight, they fixed upon the weight in vacuo of a quantity of distilled water, at its greatest density, viz., (at 39.2° Far.†), which would be sufficient to fill a cube described upon the one hundredth part of a Metre. This unit they called a Gramme.

* Distilled water is taken at its greatest density and weighed in vacuo for the following reasons:-Between certain temperatures the same volume of water differs in weight at different degrees of heat. If a portion of water at the temperature of melting ice (32° Fahrenheit, or 0° Centigrade) be placed over a source of heat, its bulk, or volume, will be observed to decrease, and therefore its density increases. This decrease of volume, or increase of density, continues until the water reaches the temperature of 39-2° F., or 4° C. If the heat be applied beyond this point the water begins to increase in volume and decrease in density. Water is therefore at its greatest density at the temperature of 39.2° F., or 4° C. Ordinary water always contains, either in solution or suspension, a quantity of saline and other substances, and the same volume, or bulk, of different specimens of water will vary in weight according to the quantity of foreign bodies contained in it.

The weight of the same size, or bulk, of any substance is greater, or less, according as the density of the atmosphere (which is constantly varying) is less or greater at different times. The greater the buoyancy of the air, the less will appear the weight of each body, and vice versa.

Therefore, to render the weight of water selected as the unit of weight free from variations arising from its impregnation with various salts, from difference of temperature, or from differences in the density of the air, distilled water at its greatest density is weighed in vacuo.

There are three different sorts of Thermometers in use:-1. Fahrenheit's which is used chiefly in Great Britain, Holland, and North America, the freezing point on which is at 32, and boiling point at 212. 2. Reaumur's, which was that chiefly used in France before the Revolution, and is that now generally used in Spain, and in some other Continental States; its freezing point is 0°, and boiling point 80°. 3. The

Such being the units, all derived from the Metre, the next step was to simplify the nomenclature of the multiples and subdivisions. This was done by prefixes from the Greek and Latin Languages, multiples being derived from Greek and subdivisions from Latin, thus:

If this system could be brought into universal use the following brief table would be common to all nations.

Celsius, or Centigrade Thermometer, now almost universally used throughout France and in the Northern and Middle Kingdoms of Europe; the Zero or freezing point is 0°, and boiling point 100. Hence to reduce degrees of temperature of the Centigrade Thermometer, and of that of Reaumur to degrees of Fahrenheit's scale, and conversely:RULE 1. Multiply the Centigrade degrees by 9, and divide the product by 5, or multiply the degrees of Reaumur by 9 and divide the product by 4 then add 32 to the quotient in either case, and the sum is the degree of temperature on Fahrenheit's scale. RULE 2. From the number of degrees on Fahrenheit's scale, subtract 32, multiply the remainder by 5 for Centigrade degrees, or by 4 for those of Reaumur's scale, and the product, in either case, being divided by 9 will give the temperature required.

The Metre is the fundamental unit of the measures of length as well as of all weights and measures. The Metre is used to measure small linear dimensions while its multiples are used for large dimensions. The distance from one place to another, as for instance on railways, is marked in Kilometres. The great dimensions of the earth, or other planets, are calculated and expressed in Myriametres. The following units are likewise employed in denoting distances:- The League of 4 Kilometres 4000 Metres; the League of 25 to a degree=4444 Metres; the Nautical League of 20 to a Degree 5556 Metres; and the Nautical mile of 60 to a Degree 1852 Metres.

=

=

Very minute lengths are reckoned in Millimetres; for instance, the thickness of a certain silver plate is 6 Millimetres 2-tenths, and this is written 6 m.m. 2.

French value.

MEASURES OF SURFACE.

Systematic name.

100 Sq. Millimetres -1 Sq. Centimetre 100 Sq. Centimetres

1 Sq. Decimetre =15.500591052192

1 Sq. Hectometre

100 Sq. Hectometres =1 Sq. Kilometre

100 Sq. Kilometres =1 Sq. Myriametre

=

Square Feet. 10.7642993418 or

=

The units most usually adopted for the measurement of surfaces, are, the square Metre, the square Decametre, and the square Kilometre, but the measurement of surfaces of very great extent is calculated in square Myriametres.

The unit for measurement of land is the square Decametre, called in this case an Are. Its subdivision is the Centiare (100th part of an Are), or square Metre, and its multiple is the Hectare (100 Ares), or square Hectometre. There is also the Decare of 10 Ares equal to about 39 Roods. This may be shown in a tabular form as follows:

100th of an Are =1 Centiare or 1 Sq. Metre=

100 Centiares

100 Ares

=1 Are or 1 Sq. Decametre:

(1 Hectare or

1 Sq. Hectometre

Approximate English value. Square Yards. 1.196046

119.6046

* The Hectare is equal to 2 Acres Rood, 35 Perches, English statute measure, nearly.

M