Portable steam-engine. 175 



manner and lifted at an appointed time, the engine is kept in Defcription of s 

 motion. The outfide appearance of thefe nozzles may be feen eam " cn 8 me - 

 at Fig. 1, c c, (Plate IX.) The rods which come out of the 

 bottom of the nozzles are kept tight by vertical ftuffing-boxes, 

 the. whole of which is hid in the drawing by the frame. 



The next is a new contrivance for producing a rotative mo- 

 tion from a reciprocating one, which not only Amplifies the 

 machine very much, but exceeds the power of the common 

 crank by nearly one-third, in confequence of its acting always 

 perpendicular to the radius of the wheel, which is done by a 

 rack and wheel, as reprefented by Fig. 2 and 3 ; and as this 

 plan of connexion diftributes the power uniformly, of courfe 

 a much lighter fly-wheel is required, which diminifhes 

 friction, &c. 



Explanation of the Plate. 



Fig. 1. is a representation of the engine: one of the cor- 

 ner columns A A, which fupports the frame, ferves Iikewife 

 for an eduction-pipe and condenfing-vefTel : the air-pump E 

 is joined to the condenfing veflel by the pipe D ; e is the pif- 

 ton-rod, and though it works out at the bottom of the cylinder, 

 it is as eafily kept tight as if it worked out at the top ; b is a 

 fimilar rod which keeps the rack perpendicular; da are the 

 two radius bars on which the brafles are fixed that fupport the 

 fhaft ; by this contrivance the wheel C eafily moves from one 

 fide to the other of the rack F. 



Fig. 2. is a view of the rack on a larger fcale, where G re- 

 prefents the wheel and D the fhaft; EE, a Hiding- bar, on 

 which is fixed the fmall roller o, ferving as a connecting link 

 to keep the wheel C always in gear ; for, when the wheel is 

 in gear on the oppofite fide of the rack, the roller o is on the 

 other fide of the plate a a ; but it will perhaps be more clearly 

 underftood by the plan, Fig. 3. where the letters reprefent 

 the fame movement as in the elevation, Fig. 2 : This defcrip- 

 tion may be eafily. underftood by thofe who already pofTefs a 

 little knowledge of a fleam-engine. 



Manchejler, OH. 5, 1805. 



Letter 



