242 REPORT—1858. 
trials and sea performances of the same ships as enable them fully to respond 
to this part of the inquiry, and they refrain from expressing any speculative 
opinion, because they have adopted the principle which they desire to recom- 
mend to the notice of the British Association, that shipping improvement is 
to be discovered by statistical record and analysis of the constructive elements 
of ships that have practically shown themselves to possess good sea-proper- 
ties, rather than by assuming the mere theories of opinionative speculation, 
from whatever source such opinions may emanate,—in short, that experience 
of actual performances at sea, statistically recorded and utilized by being 
made the basis of comparison, is the most reliable base on which to construct 
an inductive system of progressive improvement in naval architecture and 
marine-engine construction. This Committee, however, have much satisfac- 
tion in being enabled to commence this inquiry by recording the sea per- 
formance of the before-mentioned vessel Bremen, on a passage from Bremen 
haven to New York and back, during the months of June and July last, during 
the whole of which passages indicator cards were frequently taken, and the 
indicated working power of the engines ascertained. On the out passage the 
mean displacement was 2878 tons, the mean indicated horse-power was 1078, 
and the mean speed 10°28 knots per hour, giving a coefficient by the formula 
referred to=204; but on the return passage the mean displacement was 
2990, the mean indicated horse-power 1010, and the mean speed at the rate 
of 11:92 knots per hour, giving a coefficient=348. Hence the mean co- 
efficient of the out and home passage=276, being about 13 per cent. below 
the coefficient (319) obtained on the smooth-water test-trial of the ship. 
The state of the weather and the sea was also recorded daily ; it appears to 
have been adverse on the out passage, but favourable on the home passage. 
The Committee are, therefore, of opinion that, by following up this course 
of statistical record of the smooth-water trial and subsequent sea perform- 
ances of ships respectively, a tabtlar statement might be compiled, showing 
the probable ratios of the coefficients of smooth water and sea performance, 
corresponding to the various rates of speed for which steamers may be re= 
spectively powered, whence the smooth water test-trials of ships may be made 
available as approximately indicative of their sea-service capabilities as 
respects their dynamic properties. 
Such are the statistical data of the constructive elements and dynamic 
capabilities of the Bremen, and if all steam-vessels engaged in the mercantile 
transport service of Britain were equally effective as respects the mutual re- 
lations of displacement, speed, and power, that is, capable of producing a co- 
efficient of dynamic capability =319, by the formula referred to, it is probable 
that the prime-cost expenses of steam-ship transport per ton weight of cargo 
conveyed on long passages would, on the aggregate of the foreign trade of 
Britain, be reduced not less than 25 per cent. as compared with the prime- 
cost expenses incurred by steam-vessels of the average dynamic capability 
in present use. 
The effect of improved type of build on the economy of steam transport 
per ton weight of goods conveyed, is such as shows the inquiry to be of vital 
importance in connexion with the management of steam-shipping affairs. 
The public importance of improved type of build in a national point of 
view (for it is the public and not the shipowners who ultimately bear the 
brunt of expensive transport service) may be judged of from the statistical 
fact published by the Board of Trade, that no less than 899 steam-vessels 
(of which 511 are sea-going ships) were employed on the commercial trans- 
port service of Britain in 1857. The ratio in which the transport service of 
the country is performed by the aid of steam appears to be constantly on the 
