Polytechnic Association Pboceedinos. 705 



to the ends, at g, exert a uniform pressure outward throughout 

 their entire length. Leakage, at g^ where the rings are cut, is pre- 

 vented by the insertion of a tongue. Steam is also admitted under 

 them, thus securing constant pressure and tightness. The steam 

 chest, J, is bored out, and the face of the valve, K, in Figs. 1 and 

 3, is an arc of a circle of the same diameter of the steam chest. The 

 valve is a separate piece from the valve stem, X, Figs. 1 and 6. 

 Projecting from the face of the stem is the radial pin,/, which fits 

 into a corresponding hole, K, in the valve. The valve is worked 

 by this pin, but is not held rigidly by it, and is left free to adapt 

 its face to the valve seat independently of the wear of the line of 

 the stem. The stem is worked in the usual manner by the eccen- 

 tric, iV, and valve rod, M. The course of the steam through the 

 valve, steam ports, 0, cylinder and exhaust port, P, will be readily 

 understood. The heater is not shown in Figs. 1 and 3; but the 

 way in which it is attached will be seen at e, in Fig. 2. Its form 

 or location maj'^ of course be varied, as desired. Q is the governor; 

 R, the oiler. The frame S is bolted on the lower cylinder head. 

 T is the bed plate; U, pedestals; F, the key to tighten the jour- 

 nals; D\ outside bearing; /, fly wheel; Y, cap or cover over the 

 trunlv. 



" Since the cuts were made, I have greatly improved the manner 

 of attaching and driving the force pump, and made other improve- 

 ments, having introduced an entirely new set of patterns." 



Mr. Root set forth the advantages claimed to be gained by his. 

 engine, which may be thus briefly stated: Highest economy of fuel, 

 owing to greatly diminished dead weight and reduced friction; 

 greatest durability and least liability to get out of repair, owing to 

 extreme simplicity and fewness of parts (having but two parts 

 between the steam and crank pin, viz: trunk with piston cast on 

 it, and the connecting rod); and also to light side strain and wear, 

 and having large wearing surfaces; extreme compactness, the 20 

 horse power occupying a floor space of 3x4^ feet, and the 40 horse 

 power 5x6 feet; very light total weight, making a great saving in 

 freight and handling, and, owing to this and simplicity of construc- 

 tion, great saving in the cost of foundations and erections. 



In engines of this character, as formerly built, there was much 

 strain and wear upon the cylinder, piston and stuffing-boxes, result- 

 ing from the short connecting rod, which was attached to the trunk 

 at the center and opposite to the piston-head, but he had obviated 

 these defects by lengthening the connecting-rod and attaching it to 



{I»6T.] 45 



