RATIO OF SPEED OF A STEAM BOAT TO THE POWER. 03 



Mean of number of strokes, full steam . 24j Mean speed . 8'08 miles. 



Do. do. reduced steam 23 Mean do. . 7-78 



Difference . 0-3 



Steam used at full pressure. Reduced steam. 



Atmosphere . 14| Ibs. Atmosphere . 14J Ibs. 



Above do. . 3j Above do. . 1 



Total .18 15| 



Number of strokes 24 J Number of strokes 23 



Products . 441 362 



Powers employed nearly as 11 to 9, speed 25 to 24. 



FIRST REPORT ACCOMPANYING THE EXPERIMENTS ADDRESSED TO 



SIR JOHN BARROW. 



" SIR ; Woolwich, Nov. 15, 1836. 



" On the next page I have given the result of my experiments yesterday, 

 on his Majesty's steamer Lightning, from which it will appear, that reducing the steam 

 pressure from 3^ to 1 lb., makes a difference in the speed, when going with the wind, of only 

 about |th of a mile per hour ; and with her head to the wind, of less than fths mile per hour ; 

 at a medium -j^ths mile per hour ; the reduction of the steam power being between ^th and 

 |th : that is, by allowing a reduction of less than ^rd of a mile per hour, or 8 miles per day, 

 a vessel which can now carry only ten days' fuel, would, with this reduction of speed, carry 

 twelve days' fuel, and perform a voyage longer by nearly 330 miles, i. e., 2330 miles, 

 instead of 2000. 



" There are different ways in which this reduction may be effected ; viz. either by reducing 

 the pressure, as I have done, by using an engine of less power, or by causing the steam to 

 act more expansively : which will be the best is a question for the decision of an engineer, 

 all I intended to show by the experiments was, that the questions of going quickest and going 

 farthest were different. 



" I beg to return my best thanks to my Lords Commissioners of the Admiralty for the 

 facilities they have afforded me of confirming by experiment a result which is perfectly 

 consistent with theory. 



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



(Signed) " PETER BARLOW." 



SECOND REPORT, ADDRESSED TO CHARLES WOOD, ESQ. 



" SIR ; Woolwich, March 2nd, 1837. 



" In compliance with the request of Sir Charles Adam, I beg to forward 

 a. concise abstract of my experiments on his Majesty's steamers Echo and Lightning, and the 

 conclusions I draw from them, although perhaps they require to be confirmed by one or two 

 other experiments. 



