92 REPORT— 1861. 



per hour respectively, bj' reference to the Table (Section I.) it appears that 

 by increasing the speed from 10 knots to 12 knots an hour, the rate of con- 

 sumption of coal being also increased from 2 lbs. to 3 lbs. per indicated horse- 

 power per hour, the required freight charge becomes increased in the ratio of 

 49 to 72, that is, in the ratio of 100 to 14-7, or 47 per cent. ; and by increasing 

 the speed from 10 knots to 14 knots per hour, the rate of consumption of 

 coal being also increased from 2 lbs. to 4 lbs. per indicated horse-power per 

 hour, the required freight charge becomes increased in the ratio of 49 to 152, 

 that is, in the ratio of 100 to 310, being an increase of 210 per cent., or 

 more than trebled. Hence, assuming the expense or required freight charge 

 by the standard ship A, steaming at lOknots per hour, and consuming 2 lbs. 

 coal per indicated horse-power per hour, to be at the rate of £1 per ton of 

 goods conveyed, the required freight charge by ship 1^, steaming at 12 knots 

 an hour and consuming 3 lbs. of coal per indicated horse-power per hour, will 

 be at the rate of sfil Gs.Sd.per ton of goods, and the required freight charge 

 by ship I3, steaming at 14 knots per hour and consuming 4 lbs. of coal per 

 indicated horse-power per hour, will be at the rate of 363 25. per ton of goods 

 conveyed. The comparative freight charges on 100,000 tons of goods by the 

 vessels A, I,, I^, respectively, would be 36100,000 36147,000, and 36310,000. 



Hence we see how onerous are the obligations of increased speed, if at- 

 tempted to be performed with engines of inferior contruction, as respects 

 economy of fuel. 



Section K. — Freight as affected (c^tens paribus) by variations of the 

 speed combined with variations in the type of form, working economy of the 

 engines, and weight of hull. 



The object of this section is to show the effect even of small differences 

 of practical construction, when operating collectively to the detriment of a 

 ship, combined with the obligation of increased speed. 



By reference to the Table (Section K) it appears that, under the special 

 conditions of the service under consideration, by increasing the speed from 

 10 to 12 knots, with a ship of inferior type of form, as indicated by the co- 

 efficient of performance being reduced from 250 to 225, and of inferior 

 engine arrangement, as indicated by the consumption of fuel being increased 

 from 2 to 3 lbs. per indicated horse-power per hour, the weight of hull being 

 also increased 5 per cent., namely, from 40 per cent, to 45 per cent, of the 

 constructor's load displacement, — by this combination, the expense per ton of 

 goods conveyed becomes increased in the proportion of 49 to 102, that is, in the 

 proportionof J 00 to208,beinganincreaseof 108 per cent.,or more than doubled ; 

 or, assuming the freight by the standard ship A to be at the rate of £1 per ton, 

 the rate of freight by ship Kj, under the differences above referred to, 

 becomes £2 \s. Sd.; and it is to observed that if the speed be increased to 14 

 knots, whilst at the same time the coefficient of performance is reduced to 

 200, the consumption of fuel increased from 2 lbs. to 4lbs. per indicated horse- 

 power per hour, and the weight of the hull increased 10 per cent., namely, from 

 40 per cent, of the load displacement to 50 per cent., — under these conditions 

 the entire load displacement of the ship K^ will be appropriated by the weight 

 of the hull, engines, and coal, leaving no displacement whatever available 

 for cargo ; that is to say, the vessel K^ is utterly unable to perform the con- 

 ditions of the service as a mercantile steamer. 



The comparative freight charges on 100,000 tons of goods by the vessels 

 A and K, respectively would be £100,000 and £208,000. 



Having thus fully explained the Table, it may be observed that, as re- 

 spects the relation which subsists between the dynamic properties of vessel 

 A, taken as the standard of comparison in the foregoing sections, and the 



