Messrs. Editors:--Permit me now to make a few remarks in regard to an article on page 844, last volume of the SCIENTIFIC AMERICAN, entitled "Which is the Most Economical Steam Engine?" The principles laid down in that article, I think are correct.

I run a saw-mill with an engine which fills those conditions nearer than I ever saw, and I would like to give your readers a brief description of it. The cylinder is 10-inch bore, and 14-inch stroke; steam chest extends enough beyond the ends of the cylinder so that the steam travels only 2½ inches, the shortest distance possible, after leaving the valve before it reaches the piston-head, and the space between the piston-head and cylinder-head is only one-fourth of an inch, the bolt heads being counter-sunk until even. Other things about this engine are in proportion. With this engine attached to a direct acting circular mill, I can saw 2,000 feet of hard-wood inch boards in one hour.

If any of your readers can beat this, I would like to hear from them.

JOHN CARNES.