[ 743 ] 
XXVIII. SiLj^j^lement to Mr. Macquoen Eai^-kine’s Pajyer “ On the Thermodynamic Theory 
of Steamrengines with dry saturated Steam, and its agjplication to 'practice* 
Eeceived September 3, —Bead December 8, 1859. 
The foUowing additional information respecting the steam-ships referred to in the 
examples may be interesting, although it does not strictly belong to the special subiect 
of the paper. *' 
Exa^iple I.— Paddle-steamer ‘Admiral,’ built by Mr. James E. Napiee; engines 
made by Messrs. Eaxdolph, Eldee and Co.; draught 7 feet 6 inches; length 210 feet; 
breadth 32 feet; displacement 820 tons; speed with 774 indicated horse-power 11-9 
nautical miles an bom’. Effective work in driving the ship, about 604 horse-power. 
Available heat expended per hour in foot-pounds per indicated horse-power, 
1,980,000 1,980,000 
efficiency of steam 0’123 — 16,100,000. 
Coal burned per indicated horse-power per hoiu’, 2-97 lbs. 
Available heat of combustion of one pound of coal, 
16,100,000 - ^ 
2 ^ 9 ^ =5,420,000 foot-lbs. 
The total heat of combustion of one pound of the coal employed being roughly esti- 
mated at 10,000,000 foot-pounds, it appears that the efficiency of the furnace and boiler 
was about 0-542. 
The boilers were improved marine boilers of ordinary proportions. 
^IPLE II.— Screw-steamer ‘Thetis,’ built by Messrs. C. Scott and Co. ; the engine 
made by Messrs. Eowah and Co. 
AvaUable heat expended per horn- in foot-lbs. per indicated horse-power, 
1,980,000 _ 1,980,000 
efficiency of steam 0-192 — 10,312, 500. 
Coal burned per indicated horse-power per hour, during an experiment of one hour’s 
duration, 1-02 lb. 
Available heat of combustion of one pound of the coal employed, 
10,312,500 
p:Q 2 =10,110,000 foot-pounds. 
The coal used was of very good quality; and its total heat of combustion per pound is 
* Philosopliical Transactions, Part 1 . 1859, p. 177 ; Proceedings of the Eoyal Society, January 1859. 
