432 Miscellaneous Intelligence. 
that is, as 62890: 142x615, or as 72:49, the same ratio as 
the preceding. ‘The success of the engine in this form will depend 
entirely upon the heating apparatus. Should that be no more efficient 
than the former, the failure will be more signal, because of the increased 
demand made upon it. It is to be presumed, however, that the invent- 
or’s attention is now directed mainly to this point, and that his attempts 
at improvement may not be entirely fruitless. 
The formula for mean pressure (page 248 of this volume) may be 
made entirely general, by substituting a letter, as IJ, to stand for the 
pressure against which the engine works. It may also be rendered 
more simple in appearance by making the following substitutions. Put 
L vy 
&! =u, and Pe Bec With these changes, it takes the following form, 
which is here given in full, in consequence of the typographical error 
in the former article. 
ke -% 
Pie [ em ~ aD ar ll -1)- Ta =B'n") +m - 1 | 
In Appleton’s Mechanics’ Magazine for July is contained a very able 
and satisfactory examination of the general theory of the caloric engine 
by Maj. J. G. Barnard, of the U. S. Engineers. As the article in this 
Journal for September appeared considerably later, in the order of 
attainable without di culty. From what has already been said above, 
mains to be seen. 
2. The Conical Condenser, a Telescopic Appendage; by Lieut. 
E. B. Hunt, Corps of Engineers, U.S. A., (Read before the Am. 
hardly anticipate that this arrangement will be of practical soexek 
th 
__* A similar reason must prevent, in the present number, any allusion to the con- 
tinuation of Maj. Barnard’s investigation, which, it is understood, is to appear 
