64 



APPENDIX. 



" It is well known, that the resistance of water to a body moving in it increases much more 

 rapidly than in the proportion of the velocity, and therefore, that the quantity of fuel requisite 

 to increase the speed from any given velocity, as for example, from 9 miles to 9| miles, 

 would be much more than in the latter proportion : in fact, by being content with the former 

 speed, the same fuel would in some cases carry the vessel 100 or 200 miles farther than with 

 the latter. 



" This was my theoretical view of the subject ; and by permission of the Lords Commis- 

 sioners I put it to the test of experiment in the two vessels above named ; and the result was, 

 that by reducing the power, and therefore the expenditure of fuel, one-sixth, the speed was 

 reduced only one twenty-fourth : and this result is in a great measure confirmed by the prior 

 experiments of Captain Oliver on his Majesty's steamer Dee. 



" I consider, therefore, that, it would be desirable, that the captains in command of his 

 Majesty's steam vessels should be made acquainted with the facts, and that they should be 

 recommended, when their vessels are employed in services which do not require the greatest 

 speed (at all cost), and when wind and weather are favourable, to work with their steam 

 gauge at a less pressure above the atmosphere than at present. 



" This may be done by allowing their fires to act with less energy, without requiring any 

 other change ; and the full power will be always at command if any circumstance should 

 require it. 



" There can, I think, be no doubt, that this practice in such cases as I have supposed, 

 would allow the same distance to be run at 9 miles per hour, with ith less fuel, than if the 

 speed were forced all the voyage to 9^ or 9i miles per hour. 



" I have the honour to be, Sir, your obedient servant, 



(Signed) "PETER BARLOW." 



The experiments on her Majesty's ship Dee, alluded to in this Report as confirming those 

 on the Echo and Lightning, are as follows. 



TABLE VII. Experiments on relative speed and power of his Majesty's ship Dee, 

 on her passage from Portsmouth to the Downs. Tonnage, 705 ; power, 200 ; 

 boilers, iron ; pressure on the safety valve, 3^ Ibs. ; wheels, radiating ; manu- 

 facturers, Maudslay and Co. 



