474 Steam Engine^> 
uegularly continued, each cylinder being alternately half filled with 
steam. 
The fiistons act simultaneously^ at right angles with each other^ 
and one is at its maximum when the other is at its minimum, so 
that there is no necessity for a balance wheel as a reservoir of pow- 
er : for when one piston ceases momentarily to act, the other in- 
stantaneously continues the motion in the same direction. The 
power is communicated to crank wheels worked by shackle bars at- 
tached to each piston. If the steam be stopt off at one half, and 
left to act by its expansive force, the gain is half a cylinder full of 
steam at each stroke. There is nothing new in two cylinders, or 
in -working by expansive steam, but the getting rid of the balance 
wheel by the simultaneous action of each piston in the manner 
above described, I think is new. 
Mr. Latrohe of the same place, is erecting a manufactory for 
.steam engines, in which he proposes to make some improvements 
pn the construction of Boulton and Watt : but whether to be used 
solely for w'ater navigation, or for sale, I know not yet. 
So much exertion, and by such men, affords ground to hope 
that at no distant time, improvements may take place, that will put 
our Engineers of America, upon a par at least with those of Eng- 
land. But of all the attempts to vary from the common construc- 
tion, I have seen none that promises so well, as those of Mr. Dow- 
ers of Philadelphia. I have carefully examined his drawings, and 
I think he has skilfully combined a series of improvements, that 
if put in practice, with great attention to ipechanical accuracy, will 
go near to supercede every variety of steam engine now in use. 
These improvements contemplated for a double engine, consist in 
1st. A more perfect mode of condensing, by the applica- 
tion of exposing a large and thin metallic vessel containing the 
steam, to the action of cold water, as the Rev. Mr. Cartwright 
proposed — —and the common method of condensing by injecting 
the spray of cold water. A plan nearly similar to Mr. Dowers* 
condenser, is suggested, p. 82 of this V'olume. 
2iy. Using perpetually the same Water, for the boiler, the con- 
denser, and injector; without diminution or the necessity of addi- 
tion ; except what may arise from imperfections in the workman- 
sliip of the vessels. In which it is not easy, always to guard against 
;,team leaks, and water leaks. The wormanship being good, this 
v»)gine must work wiih a smaller supply of water than any other 
) cl known. 
