188 REPORT—1840. 
Additional Notice concerning the most xconomical and Effective Pro- 
portion of Engine Power to the Tonnage of the Hull in_ Steam 
Vessels, and more especially in those designed for long Voyages. 
By J. Scorr RussE.t. 
After describing the unsettled state of opinion and practices on this 
subject, Mr. Russell entered into a general examination of the subject, 
from which the following are extracts :— 
‘We may now proceed to investigate the question of best proportion, 
or the point where the attainment of high speed is accompanied by 
absolute saving of fuel, as compared to lower velocity. 
«‘ We merely take it for granted, that the speed through the water 
will be nearly as the square root of the power, according to the 
general law of the resistance of fluids; that the resistance offered 
by bad weather or adverse winds has been ascertained, and is deter- 
mined on a particular station ; that is, that it is known that on a given 
station, a given vessel, with a given power, makes a voyage in adverse 
circumstances in, suppose, double the time of her most prosperous 
voyage ; (say her most prosperous voyage in 14 days, and her adverse 
voyage in 24 days, being a retarding power of 10 days out of 24;) we 
take this retardation of ten days as the measure of the retarding power 
of adverse weather in the given circumstances. 
Let h be the power, v the velocity, f the fuel consumed, ¢ the} 7, , given ves- 
time in good weather .... ....sceccereecsecsrceecsscscsscsces aunaacteon 
Metts ucceeseees <= panes bona Hosace ae Si atenene sees esener isa 3 ft eee & 
Dad'weather ‘ssssudedsssatar,scasceesetes-400 Sosesscereccadeesae 7 
Let h! be the power, v" the velocity, f” the fuel consumed, ¢" the) Inanother ves- 
time in good wWeather.......sssssessccsecseccesecee ascedeweaese |. GOK Bs pReater 
Wetssvstocs cesses vasee OMe seeuenss saceshe penesexeceanceces as See 10 on the 
bad weather ss..<,se-s<eseeess Reade tiatesesdtisnessasan ema .J same station. 
Also, let r represent the consumption of fuel per horse-power per hour, 
And ... s the length of the voyage or distance performed.” 
By investigating, Mr. Russell obtains the general formula— 
—y?2 
v2 = (A), 
wy 
2h 
and deduces the following consequences :-— 
“It appears that a vessel has its power in the most ceconomical pro- 
portion to its tonnage, on a given station, when its worst voyage ‘loes 
not exceed the time of its best in a greater proportion than V2 to 1, 
that is, than 14 to 10, or 7 to 5. 
“It further appears, that the consumption of fuel in the worst voyage 
will not exceed that of the best voyage in a greater proportion than 
10 to 7; that is to say, for 70 tons of fuel burnt on a good voyage it 
will not be necessary to carry more than 100 tons in order to provide 
against the worst. : 
“Let us take as example a Transatlantic steam-ship, which has a — 
proportion of one-horse power to four tons of capacity, her unfavour- — 
