90 REPORT 1861. 



cent. ; or, assuming the freight charge by the standard ship A, of which the 

 coefficient of performance is 250 and rate of consumption 2 lbs. per indicated 

 horse-power per hour (giving a coefficient of dynamic duty 14,000), to be at 

 the rate of £1 per ton of goods conveyed, the rate of freight by ship E^, of 

 which the coefficient ofperforniance is 200, and consumption of coals 3lbs. per 

 indicated horse-power per hour (coefficient of dynamic duty 7467) becomes 

 ,361 4s. per ton, being an increase of 20 per cent., and by ship E^, of 

 which the coefficient of performance is 150, and the consumption of coal at the 

 rate of 4 lbs. per indicated horse-power per hour (coefficient of dynamic 

 duty 4200), the rate of freight becomes £1 15s. Wd., being an increase of 

 79 per cent, per ton of goods conveyed under the conditions referred to. 

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

 Ej, E,, respectively, would be 36100,000, ^6120,000, and ^179,000. 



Hence, in the control of steam-shipping, we see the importance of the co- 

 efficient of dynamic duty (column 7), as indicating the economic efficiency 

 of the ship in a mercantile point of view, with reference to the merits of her 

 hull and engine construction being made a subject of contract stipulation. 



Section F. — Freight as aWected (cceteris paribus) by variations in the size 

 of the ship combined with variations in the constructive type of form and in 

 the working economy of the engines. 



By reference to the Table (Section F), it appears, under the special con- 

 ditions of service under consideration, that by the size of the ship being 

 reduced from 5000 tons displacement to 3000 tons displacement, combined 

 with an inferior type of form, as indicated by the coefficient of performance 

 being reduced from 250 to 150, and an inferior construction of engine, as 

 indicated by the consumption of coals being increased from 2 lbs. to 4 lbs. per 

 indicated horse-power per hour, the expense or freight charge per ton of 

 goods conveyed becomes increased in the ratio of 49 to 113, that is, in the 

 ratio of 100 to 230, being an increase of 130 per cent.; or, assuming the 

 freight by the standard ship A, of 5000 tons, of which the coefficient of per- 

 formance is 250, and the consumption of coal at the rate of 2 lbs. per indicated 

 horse-power per hour, to be at the rate of ^1 per ton of goods conveyed, the 

 rate of freight by ship F^, of 4000 tons, of which the coefficient of per- 

 formance is 200 and the consumption of coal at the rale of 3 lbs. per indicated 

 horse-power per hour, will be a61 5s. '2d., being an increase of 26 per cent., and 

 by ship Fj, of 3000 tons displacement, of which the coefficient of performance 

 is 150 and the consumption of coal at the rate of 4 lbs. per indicated horse- 

 power per hour, the rate of freight becomes ^62 6s., being an increase of 130 

 per cent, per ton of goods conveyed under the conditions referred to. 



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

 A, Fj, F,, respectively, would be ^6100,000, 36126,000, and ^6230,000. 



Hence also we observe by comparison of ships E.^ and F,, how important 

 becomes the question of magnitude when ships of inferior dynamic duty are 

 employed on a given service, the comparative freight charges on 100,000 tons 

 of goods conveyed by the vessels E, and F^, on the service referred to, being 

 ^6179,000 and 36230,000, being an increase of 28 per cent, solely in conse- 

 quence of the magnitude of the ship being reduced from 5000 tons displace- 

 ment to 3000 tons, the coefficient of dynamic duty (4200) being in both 

 cases the same. 



Section G. — Freight as affected (cceteris paribus) by variations of the 

 steaming speed at which it is required that the service shall be performed. 



It is proposed to illustrate this most important elemental consideration by 

 reference to rates of speed within the range of present practice, namely, from 

 10 to 14 knots per hour. 



