Se 
a 
W. A. Norton on Ericsson's Calorie Engine. 409 
The numbers given in the second column inclnde the weight 
of the boilers, water in boilers, coal bunkers, and all appurtenan- 
ces, together with the weight of the paddle wheels, ~ 
It appears from this comparison that, in proportion to the actual 
lorse-power, the weight of the Ericsson’s engines is about three ° 
times as great as the ordinary weight of the engines of sea 
steamers; and in proportion to the estimated power, more than 
/ per cent. greater. 
3. Space occupied by the Engines. 
_This point has been attentively considered by a correspondent 
of the Journal of the Franklin Institute (see the second February 
number of the Journal, p. 128), who shows that here also the 
advantage is on the side of the steam engine ;—the economy of 
space being nearly twice as great. 
4, Friction and other Resistances. 
We may obtain an estimate of the comparative resistance, in 
the two forms of engine, to be overcome by the moving power, 
by teducing the power of several steam engines to the speed and 
immersed midship section of the Ericsson on the occasion of the 
inal trip; that is, calculate what reduced power they would have 
if they were just capable of propelling with a speed of 7 or 74 
Son at 17 feet draft, i. e. 520 square feet. This may be effected 
by observing that the horse-power will vary nearly as the cube 
A Ca PTI ees REDUCED HORSE-PU WER. 
Horse-power, | Speed. 4 miles, 
a ae | miles. 
539 84 
2290 4 
Util + 471 
S a j 576 + 183 
o. 
Stcox Sens, Vol. XV, No, 45.—May, 1853. 
