244 REPORT—1858, 
struction of the engines, propeller, and boilers; for a good type of hull, pro- 
pelled by an inferior construction of machinery and boilers, or an inferior 
type of hull propelled by a good construction of machinery and boilers, may, 
by the above formula, produce equal results. This Committee, however, 
consider it of vital importance to the promotion of the objects of this in- 
quiry, viz., “the maturing of a system of statistical record conducive to the 
improvement of naval architecture,” that the owners and charterers of ships, 
and the directors of shipping companies or agents by whom shipping affairs 
are conducted, should themselves have the means of ascertaining the relative 
dynamic merits and working condition of their ships without any reference 
whatever to the professional assistance of builders or engineers, but be enabled 
to judge for themselves whether the performance be good or bad by refer- 
ence to the data afforded by their counting-house records ; and this desirable 
object may be at once effected by the displacement of the ship being known, 
and by substituting in the foregoing formula the consumption of fuel in a 
given time (say the weight in ewts. (W) consumed per hour), in lieu of the 
expression for power, and regarding the hull, machinery, and boilers collect- 
ively as an integral equipment of which the coefficient derived from the 
formula pia * indicates the dynamic condition with reference to the 
dynamic condition of other vessels tested by the same rule, viz.:—Miultiply the 
cube of the speed by the square of the cube root of the mean displacement, 
and divide the product by the consumption of fuel per hour expressed in 
ewts. The quotient indicates the relative dynamic condition of tie vessel. 
For example: a steam-ship (A) performed out and home voyages amounting 
to ’7200 nautical miles in 652 hours, being at the average speed of 11°04 
knots per hour, the consumption of coal was 1519 tons, or 30,380 ewts., 
being at the rate of 47 ewts. per hour, and the mean displacement was 2934. 
tons. Hence the coefficient of dynamic duty indicative of the merits of the 
. 3 2 ¢ . 
performance on this occasion is i ea 
Again, another vessel (B), with a mean displacement of 840 tons, attains on 
long-continued service, the average speed of 12°78 knots per hour, with the 
average consumption of 50°3 Sat coal per hour, giving a coefficient of 
dynamic duty Ge i) x 89 __ s609, Thus, in one case 
(A), the coefficient of dynamic duty, based on the consumption of fuel, is 
5870, whilst in the other case (B), it is only 3693 ; that is, one ewt. of coal 
in A performs as much dynamically effective work as is performed by 1,8, 
ewt. in the case of B, a discrepancy which may well induce professional 
inquiry being instituted by the shipowner, whether the inferior performance 
of B is occasioned by inferior type of form, or foulness of bottom, or inferior 
principle of mechanical appliances, or inferior management, or bad coal; for 
these causes, combined, or indeed either one of them alone, may be sufficient 
to account for the result. 
Now, what are the all-important elements of construction thus proposed to 
be embraced in public records, and thereby made known to the purchasers 
and charterers of ships with a view to enable such parties to test the economic 
working capabilities of ships, so conducive to the reformation above referred 
to? Why, by the rule above enunciated, the displacement corresponding to 
the constructor’s load draught at which the ship may be tried, and to which 
approximately, as a general rule, the ship may be loaded, becomes the only 
item of statistical data that requires to be officially recorded, for the test trial 
