120 REPORT—1857. 
having weight-carrying capability or weight-tonnage of 2000 tons, with aship 
of the same capability for carrying weight, but of the type I, namely, length 
eight times the beam, and load-draught one-third the beam. By Table A 
(columns 25, 26, 27 and 28), it appears that the ship of type D, of 2000 
tons weight tonnage, will be 1680 tons builders’ tonnage O.M., 1400 tons 
gross register tonnage N.M., and 3680 tons load-displacement ; and by Table 
B, it appears that 950 ind. h.p. would propel this ship at the speed of 10 knots 
per hour; the consumption of coal at the rate of 34 Ibs. per indicated horse- 
power per hour, would be 30 cwts. per hour; and supposing the engines, 
boilers, &c. to weigh one ton weight per five ind. h.p., the weight of these 
will be 184 tons; this ship may therefore be expected, on the data of the 
said Tables, to make a passage of 3500 nautical miles in 350 hours, consu- 
ming 525 tons of coal, and carrying 1291 tons weight of freight cargo. But 
what would be the case with the vessel of 2000 tons weight tonnage of type 
I? It appears that the builders’ tonnage O.M. would be 5120 tons, the re- 
gister tonnage N.M. 2720 tons, and the load-displacement 5480 tens; and by 
Table B, it appears that to propel this vessel at 10 knots per hour would 
require 1240 ind. h.p., these engines weighing 248 tons, and the consump- 
tion of coals 39 ewts. per hour; so that, on the data of the said Tables, this 
ship on the type I may be expected to make the passage of 3500 nautical 
miles in 350 hours, consuming 682 tons of coal, but carrying only 1070 tons 
of freight cargo. Hence it appears that with vessels of type D, we have ex- 
penses proportional to 1400 tons register N.M., and 950 ind. h.p., with in- 
come proportional to 1291 tons weight of freight ; while with the ship of type 
I we have expense proportional to 2720 tons register N.M., and 1240 ind. 
h.p., with income proportional to only 1070 tons weight of freight; that is, 
the comparative prime cost expenses of transport in these two cases (assu- 
ming the cost incidental to one ind. h.p. to be equal to that of one ton of gross 
register tonnage) will be in the proportion of 
1400 + 950 2720 + 1240 
1 beech aae aaa Re ae 
or in the proportion of 1 to 2. Such is the effect of mere difference of pro- 
portion or type of build on mercantile steam transport economy. ‘This 
example of a difference or extra cost of 100 per cent. on the prime cost rates 
of freight per ton weight of cargo conveyed on the same passage, and at the 
same rate of speed, is evidently occasioned by the load-draught of water being 
two-thirds of the beam in one case, that of the vessel D, and only one-third 
of the beam in the other case, that of the vessel I; and yet we see that the 
type or proportion of small load-draught in proportion to beam is a type or 
proportion of build, towards which the progressive increase in the size of 
shipping is gradually leading mercantile practice, as exemplified in the most 
extraordinary maritime enterprise of the present day, the ‘ Great Eastern. 
The mechanical advantage which attends progressive increase of size as 
measured by load displacement, is conspicuously shown by Table B, whereby 
we observe that a vessel of 250 tons displacement requires 274 ind. h.p. to 
attain the speed of 12 knots per hour, being very nearly in the ratio of one 
ton displacement to one h.p.; but, if the ship be 2000 tons, the ratio of dis- 
placement to power to attain the same speed (12 knots) will be 2 to 1; with 
_a ship of 9000 tons it will be 3 to 1; and with a ship of 20,000 tons it will 
be 4to 1. Hencea ship of the reputed size of the ‘ Great Eastern,’ viz. about 
25,000 tons load displacement, will require proportionally only about one- 
fourth of the power to attain a given speed that would be required by a ship 
of 500 tons displacement. Hence the great advantage of size, provided the 
