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A404 W. A. Norton on Ericsson’s Caloric Engine. 
The two estimates of the speed through the water are quite 
different, but the number of revolutions of the paddle wheels, as 
stated by different authorities, lies between 9 and 94. The num- 
ber of revolutions, about which there is but little disagreement, 
will enable us to obtain by calculation a pretty close approxima- 
tion to the speed. For this purpose we have the following data. 
Diameter of the wheels from centre of pressure to centre of pres 
sure, 30} feet; paddles 32 in number, on each wheel, and 104 
feet long by 16 inches deep; dip of the wheels 44 inches. ‘The 
following quantities were obtained by calculation, viz: number 
of paddles in water, on each wheel, 7; immersed paddle surface 
on both wheels, 196 square feet; area of midship section, at 17 
feet draft, 520 square feet; ratio of immersed paddle surface to 
area of midship section, 1 to 2653; same for steamship Arctic, 
1 to 1662 (see Journal of Franklin Institute for Jan., 1853, No. 
1, p. 33); slip of wheels of Arctic, 19-32 per cent. From which 
we find the slip of the wheels of the Ericsson, on the trial trip, 
to have been 24:4 per cent. The distance passed over by the 
centre of pressure of wheels was 9°88 miles per hour. Hence, 
allowing for the slip, the speed of the ship was 7-47 miles per 
our. If we allow for the less oblique action of the paddles in 
the case of the Ericsson than in that of the Arctic, we find the 
speed to have been 7:57 miles per hour (the slip of the wheels 
being reduced to about 23-4 from this cause). 
here is some little uncertainty with regard to the area of the 
midship section. Although I have not succeeded in obtaining 
the data necessary for an exact calculation of this element, the 
information furnished me in reference to the model of the Erics- 
son as compared with that of the steamers of the Collins line, 
has enabled me to approximate very nearly to a correct result. 
The rule by which the calculation was made has been tested by 
trying it upon a large number of ships. It gives results, 10 a 
most every instance, a little too small; thus for the Arctic, | ; 
result is 662, and the true area is 685. The greater “dead-rise 
of the Ericsson may diminish the area, as compared with the 
Aretic, some 30 square feet; which would make it about 510 
sqnare feet. It in all probability, lies between 520 and 500. 
_ Af we take it at 500, the slip of the wheels comes out 23 pet 
cent., and the speed of the ship 7-61* miles. In view of all that 
has now been stated, we may conclude that the average a 
the on through the water, on the trial trip, could not we 
excested 7% statute miles per hour; and was most pro : 
about 74 miles. 
Horsepower of the E'ricsson’s Engines, developed on the — 
trip. Working pressure of air, 8 lbs.+15 Ibs.  Sapposing # 
comes out 7°88 miles, ced oe apes ae y Genie 
