ON CONSUMPTION OF FUEL, &c. 251. Given the quantity of coal on board on leaving port, and the consumption in a given number of days: to find what quantity remains on board. EXAMPLE. Ex. The quantity of coal on board on leaving port is 350 tons, the consumption in 17 days is 258 tons II cwt. I qr. 25 lbs.: what quantity remains on board? 252. Given the daily consumption of coal and the speed per hour, to find what the consumption would be in a voyage of a given number of knots. RULE XCVIII. 1°. Multiply the speed per hour by 24; the result is the number of knots the ship makes per day. 2o. Next, say, as the knots sailed per day is to the knots in the voyage, so is the consumption per day to the consumption for the voyage. EXAMPLES. Ex. 1. If the consumption of coal is 36 tons per day to produce a speed of 10 knots, what is the consumption on a voyage of 960 knots ? Speed per day = 10 knots X 24 = 240 knots. Ex. 2. If the consumption of coal is 20 tons per day to produce a speed of 12 knots, what would the consumption be in a voyage of 1200 knots ? 253. Consumption of Coal and Speed of Vessel.-The consumption of coal varies as the distance multiplied into the square of the speed, or as the cube of the speed itself. EXAMPLES. Ex. 1. Suppose a ship uses 200 tons of coal in a voyage of 500 miles, and steams at 10 knots an hour: what quantity would take her 1000 miles at 6 knots an hour? Ex. 2. During a voyage of 1200 miles, performed at an average speed of 10 knots, the total consumption of fuel is 150 tons: it is required to know the consumption for a voyage of 2400 miles at a reduced speed of 8 knots. Ex. 3. If the consumption of coal per day be 16 tons to produce a speed of 9 knots per hour, how many knots should she steam when the consumption is 12 tons ? Ex. 4. Steaming at 11 knots an hour 4 tons of coal are used: find the consumption when steaming 9 knots. 93 X 4 113 : 93 :: tons : x == 219 tons. Ex. 5. The average rate of speed of a ship last voyage was 7 knots per hour, with a consumption of 11 tons per day; this voyage (her boilers having been renewed), she makes 8 knots per hour: what is the present consumption ? Ex. 6. If a ship of 350 1.H.P. steams 8 knots an hour, what should be the I.H.P. of a new engine so that she may steam 10 knots. 1. EXAMPLES FOR PRACTICE. If 195 tons of coal suffice for a voyage of 1700 miles at the rate of 9 knots: how many tons will be required for a voyage of 2200 miles at a reduced speed of 8 knots ? 2. Suppose a ship uses 160 tons of coal in a voyage of 2250 miles at the rate of 8 knots: what quantity will take her 3150 miles at a reduced speed of 6 knots ? 3. If 100 tons of coal suffice for a voyage of 1000 miles at the rate of 10 knots: it is required to know the consumption for a voyage of 2400 miles at a reduced speed of 9 knots. 4. A ship made a voyage of 1900 miles at ro knots per hour, with a total consumption of 100 tons of coal: what should be her consumption for a voyage of 2320 miles at a speed of 9 knots per hour? 254. Given the consumption of coal per day and the average indicated horse-power to find the consumption per hour per indicated horse-power. RULE XCIX. 1°. Multiply the tons of coal consumed per day by 2240 (the number of pounds in a ton), and divide the product by 24: the quotient thus found is the number of pounds of coal consumed per hour. 2°. Divide this last quantity by the indicated horse-power (I.H.P.): the result is the consumption per hour per indicated horse-power (I.H.P.) EXAMPLES. Ex. 1. The consumption of coal is 81 tons per day, the average horse-power indicated is 2760: what is the rate of consumption per indicated horse-power? 81 X 2240247560 lbs. of coal per hour. 75602760 = 2'74 lbs. of coal per hour per I.H.P. Ex. 2. The consumption of coal is 37 tons per day, the average horse-power indicated is 960: what is the rate of consumption per indicated horse-power? EXAMPLES FOR PRACTICE. In each of the following examples the I.H.P. and consumption per day are given, to find the consumption per I.H.P. Ex. 1. If the total consumption of coal be 35 tons per day, how many basketsful, each weighing 63 pounds, will be burnt in a watch of 4 hours? Ex. 2. 207.4 basketsful per watch. If the total consumption of coal be 14 tons per day, how many basketsful, each weighing 58 lbs., will be burnt in a watch of 4 hours? |