Mètre 3·2808992 feet. Décamètre (= 10 mètres) 32·808992 feet. Hectomètre(= 100 mètres) 328·08992 feet. Kilomètre (= 1000 mètres) 1093·633 yards. Myriamètre(= 10,000 mètres) 6·2138 miles. Decimètre (= 1/10th of a mètre) 3·937079 inches. Centimètre(= 1/100th of a mètre) 0·39371 inch. Millimètre(= 1/1000th of a mètre) 0·03937 inch. SUPERFICIAL MEASURE Centiare (= 1 square mètre) 1·196033 square yard. Are(= 100 square mètres) 0·098845 rood. Hectare (= 10,000 square mètres) 2·471143 acres. MEASURES OF CAPACITY. Litre (= 1 décimétre cube) 1·760773 pint(61·027 cubic inches). Décalitre (= 10 litres) 2·2009668 gallons. Hectolitre (= 100 litres) 22·009668 ” Kilolitre (= 1000 litres) 220·09668 ” Décilitre (= 1/10th of a litre) ·17607 pint. Centilitre (= 1/100th of a litre) ·017607 pint. SOLID MEASURE. Stère (= 1 cubic mètre) 1·31 cubic yard. Décastère (= 10 stères) 13 cubic yards, 2 feet, 21 inches. Décistère (= 1/10th of a stère) 3 cubic feet, 918·7 cubic inches. FRESH AND SALT WATER COMPARED. FRESH. SALT. 1 cubic foot at 40° weighs 62·425 lbs. 64 lbs. 1 cubic inch at 40° weighs ·036,126 lbs. ·037,037 lbs. 1 cubic foot at 40° equals 6·242 gallons 6·2 gallons. 1 ton equals 35·943 cubic ft. 35 cubic ft. 1 ton contains at 62° 224 gallons 217 gallons. VELOCITY OF FALLING FLUIDS. Falling fluids are governed by the same laws as falling bodies. Fluid falls 1 foot in a ¼ of a second, 4 feet in ½ of a second, 9 feet in ¾ of a second, and so on. The velocity of a fluid, flowing through an aperture in the side of a reservoir, is the same that a heavy body would acquire by falling from a height equal to that between the surface of the fluid and the middle of the opening. The velocity of a fluid flowing out of an aperture is as the square root of the height of the head of the fluid. The theoretical velocity, therefore, in feet per second is as the square root of the product of the space fallen through in feet and 64·333; consequently, for 1 foot it is [Sqrt]64·333 = 8·02 feet. The mean velocity is about 5·4 feet, or 0·673. PRESSURE OF WATER AT DIFFERENT HEADS. H. = head in feet. P. = pressure in lbs. per sq. foot. p. = pressure in lbs. per sq. inch.