W. A. Norton on Ericsson’s Caloric Engine. 403 
pistons are the same, or nearly the same, while the communications 
are open; the pressure on the top of the supply piston begins at 
I5lbs., becomes 8 lbs. + 15 |bs. at the 3 stroke from the end 
(more accurately °°, ), and continues the same to the end of the 
stroke. The air is shut off from the working cylinder at the same 
fractional part of the stroke, and acts expansively to the end of the 
stoke. The mean effective pressure per square inch, for the 
Whole stroke, is then the same upon both pistons. It may be 
found in the usual manner, by the use of hyperbolic logarithms, 
Multiply this, diminished by 15 lbs., into the difference between 
the areas of the two pistons, expressed in square inches, and 
again into the velocity of the piston per minute, and divide the 
Product by 33,000, and the result will be the horse-power of one 
of the engines. 
But it is to be observed that the result thus obtained will be 
somewhat too large, for the following reasons. 1. The actual 
Presstire in the supply cylinder is greater than the pressure in the 
feceiver (8 lbs.), and the actual pressure in the working cylinder 
is less than this. 2. During the § stroke from the commence- 
ment, the outlet valves at the top of the supply cylinder remain 
tlosed, and consequently the expansive force of the air in the re- 
‘eiver must be somewhat reduced by the flow of air from it into 
the working cylinder, 3. After the cut off valve is closed, the 
elastic pressure of the air in the working cylinder during the re- 
maining 4 stroke, must be diminished somewhat by leakage. 
The effect of this leakage has not hitherto been taken into ac- 
count, . ; 
“ts PERFORMANCE. 
_ There have been two trial trips of the Ericsson, in the New 
York harbor and bay, and the ship has subsequently made a suc- 
cessful trip to Alexandria and back. On the first occasion, only 
the inventor, owners and crew were present. The perform- 
ance on the occasion of the second trip (Jan. 11th, 1853) was 
Witnessed by the members of the New York press, and a few 
si gentlemen, present by invitation. The results of ' me 
fave been published in all the New York papers, but the differ- 
ent accounts disagree very materially on most of the important 
Points, By personal inquiry and by consulting the most reliable 
accounts I have endeavored to come as near to the truth as pos- 
sible, The following are the principal results: 
No. of revolutions of wheels per minute, (according to 
Rs Gs eae 
Same, Seientie ding to other most reliable authorities), . ae 
Speed through the water, (according to Ericsson), ‘ 
alt tt 6 geet poets to other authorities), 7 — “ 
Working pressure in receiver, per square inch, . ‘ A ice 
Consumption of anthracite coal in 24 hours, . . 6 tons. 
sueen 
