BEPORT OF THE POLYTECHNIC ASSOCIATION. 35 



Icind which has long been in common use for simihxr purposes. 

 These pipes can either be stacked in the room w|^ere the heat is 

 to be used, or in an air chamber from which the air is to be con- 

 ducted to the upper rooms. The regulation of the heat by the 

 pressure of steam is not new, but Messrs. Baker & Smith have a 

 modification of the connections which seems to be efficient. The 

 most valuable novelty in their apparatus is the regulation of the 

 admission of cold air into the warm air chamber — this seems to 

 be essential when there is danger from the formation of ice in 

 the pipes. It has been the aim of Messrs. Baker & Smith to 

 make a steam heating apparatus wliich can be comprehended and 

 managed by an ordinary domestic without the aid of an engineer, 

 and this is accomplished in part b}^ making the machine regulate 

 itself. 



This apparatus, as an improvement on the steam-heaters, is 

 entitled to a silver medal, 



Mitchell's Type-setting and Distributing Machines. 



Type-setting and distributing machines operating in the estab- 

 lishment of J. F. Trow, No, 50 Greene street, invented by Wm. 

 Mitchell of Brooklyn. 



These admirable machines deserve high commendation. The 

 inventor has not attempted too much by endeavoring to make 

 his type-setter select every character to be found in the printer's 

 case, but he has succeeded in all he has attempted. 



This machine, properly managed, will do about the work of 

 two compositors. The main adjustment of the type conveyors, 

 which will deliver the type in their proper turn and place, is an 

 invention, the final completion of which must have cost the inven- 

 tor a vast amount of time and thought. The distributor is 

 equally ingenious, and in its selection of the various letters and 

 placing them in their proper order, the machine seems to possess 

 a human endowment. This selection is regulated by a nick upon 

 the side of each type, which is the infallible guide to its proper 

 depository. These machines can be moved and managed by a 

 boy. Mr, Trow deserves great credit for introducing these use- 

 ful innovations, which have been in successful operation for seven 

 or eight years. 



The examiners think Mr, Mitchell is entitled to a gold medal. 



S. D. TILLMAN, Secretary. 



New York, February 27, 1862. 



