ON FREIGHT AS AFFECTED BY DYNAMIC PROPERTIES. 91 



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

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

 10 to 12 knots per hour, the expense or required rate of freight per ton of 

 goods conveyed becomes increased in the ratio of 49 to 64, that is, in the 

 ratio of 100 to 131, being an increase of 31 per cent.; and by increasing the 

 speed from 10 to 14 knots, the expense, or required rate of freight per ton of 

 goods, becomes increased in the ratio of 49 to 93, that is, in the ratio of 100 

 to 182, being an increase of 82 per cent. Hence, assuming the freight by the 

 standard ship A, of 5000 *ons, making a passage of 3000 nautical miles at 

 10 knots per hour, to be at the rate of £1 per ton weight of goods conveyed, 

 the rate of freight by ship Gj, steaming at 12 knots per hour, will be required 

 to be £1 6s. 2d. per ton weight of goods conveyed, and the rate of freight by 

 ship Gj, steaming at 14knots per hour, will be required to be £1 I6s. 5d. per 

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

 of goods, by the vessels A, Gj, G.„ steaming at 10, 12, and 14 knots per hour 

 respectively, would be jei00,000,"3ei31,000, and 36182,000. 



Hence we see how onerous are the obligations which usually impose on 

 mail-packets a rate of speed higher than that which would be adopteil for 

 prosecuting a purely mercantile service ; and as no service can be permanently 

 and satisfactorily performed which does not pay, it follows that the inade- 

 quacy, if any, of a high-speed postal subsidy must be made "up by surcharge 

 on passengers and cargo, and is therefore, pro tanto, a tax upon trade. 



Section H — Freight a.s SiSecieA {cceteris paribus) by variations of the size 

 of ships combined with variations of steaming-speed. 



We will suppose the size of the ships to be 5000, 4000, and .3000 tons 

 displacement, and the steaming-speed to be at the rates of 10 knots, 12 knots, 

 and 14 knots per hour respectively. 



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

 conditions of the service under consideration, by reducing the size of the ship 

 from 5000 to 4000 tons, and increasing the speed from 10 to 12 knots per 

 hour, the expense or required freight charge becomes increased in the ratio 

 of 49 to 66, that is, in the ratio of 100 to 134, or 34 per cent. ; and by re- 

 ducing the size of ship from 5000 to 3000 tons, and increasing the speed 

 from lO knots to 14 knots, the required frfight charge becomes increased 

 in the ratio of 49 to 1 19, that is, in the ratio of 100 to 243, being an increase 

 of 143 per cent., or a multiple of 2y times nearly. Hence, assuming the 

 rate of freight by the standard ship A, of 5000 tons, steaming at 10 knots, to 

 be at £1 per ton weight of goods conveyed, the required rate of freight by 

 ship Hj, of 4000 tons, steaming at 12 knots, will be £i 6s. 10c?., and the 

 required rate of freight charge by ship H^, steaming at 14 knots per hour, 

 will be at the rate of £2 8s. Id. per ton weight of goods conveyed. 



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

 A, Hj, H,, respectively, will be ^6100,000, ^ei 34,000, and ^6243,000. 



Hence also we observe by comparison of ships G^ and H^, how important 

 becomes the question of magnitude when the service demands a high rate of 

 speed, the comparative freight charges on 100,000 tons of goods conveyed 

 by the vessels G^ and H^, on the service referred to, being £182,000 and 

 £243,000, being an increase of 33y per cent., solely in consequence of the 

 ship being reduced from 5000 tons displacement to 3000 tons, the coefficient 

 of dynamic duty (14,000) being in both cases the same. 



Section I. — Freight as affected by variations of speed combined with 

 variations of the working economy of the engines. 



Assuming the rate of speed to be 10 knots, 12 knots, and 14 knots, and 

 the consumption of coal to be 2 lbs., 3 lbs. and 4 lbs. per indicated horse-power 



