Report ufthe Hcmse vf Commons on Sieam-Boats. 127 



In adapting the quantity of steaming power to vessels, the ob- 

 ject, as yet, seems to have been to obtain a j^reat degree of speed 

 in smooth water. But this principle, in respect to sea vessels, 

 is clearly an erroneous one ; for the proper object is not so 

 much having great speed throiigh smooth water, as a certain 

 progress, even at a very moderate rate, against a head sea in 

 a heavy gale of wind. 



The quantity of power sufficient to accomplish this is that 

 quar.tiiy which should be applied to every sea boat, if her size 

 and draught of water will admit of it. Mr. Donkin says, 

 " From the observations I have made in most vessels, I have 

 found them to have too little power for the size of the vessels:" 

 he recommends that the engines should be made considerably 

 larger than necessary for giving the vessel the required velocity 

 in still water : he sa^'s, " There is no other disadvantage from 

 increasing the power of an engine than the room it requires 

 and the expense ; but to counterbalance these, there is an ad- 

 vantage in not being obliged, at all times, to work the engine 

 up to the extent of its full power ; less fuel would be consumed, 

 and the engine v/ould be less likely to go out of order." 



Mr. T. Bramah says, " You cannot have too much power ; in- 

 deed it is always of advantage to have as much power as can be 

 obtained." — Messrs. Maudslay and Field say, "With regard to 

 the quantity of power proper to put into a sea-vessel, the only 

 limit should be the weight of the engine and fuel the vessel 

 will carry and contain ; no vessel ever had too much power, 

 even in still water, much less when contending against a heavy 

 head wind." " Two engines," they go on to say, " of half 

 the power each, are more manageable, and jiossess many ad- 

 vantages over one of the whole j:)ower ; they produce a per- 

 fectly uniform rotation in the wheels, and are not subject, like 

 single engines, to be stopped on the centre in heavy seas; and 

 in case of injur}' to one engine, the other is available." 



It appears from Mr. Brown's evidence, that two fifty-horse 

 engines will weigh from 20 to 25 tons more than two forty- 

 horse engines; tiie weight of the hitter, with coal and water 

 complete, being 100 tons. The additional expense would be 

 about 1000/.; the expense of two forty-horse engines being 

 abcttit (jOOO/. According therefore to the opinions already 

 stated, v/hen a vessel will contain tv/o fifty-horse engines, it 

 will be decidedly better to have them of this power than two 

 of forty-horse ])()wer. 



Notwithstanding the great and rajjid progress which steam- 

 navigation has made, it is still considered by the ablest engi- 

 neers to be only in its inlimcy : experience suggests, in every 

 new vessel and engine, some improvement to be made, or some 



defects 



