704 Transactions of the American Institute. 



against the whistle and cause an alarm. About 2,200 of these 

 machines are in use at present. 



A TRACK CARRYING-CAR. 

 Mr. Kershaw exhibited a model of a section of a railway car 

 carrying its own track. The wheel of the car is inclosed in a rim 

 or ring of several times greater diameter than that of the wheel, 

 which, as it revolves, forces the ring to turn, forming the track as 

 the wheel runs on its inner periphery. The plan was considered 

 ingenious, but of no practical utility. 



ROOr 8 TRUNK ENGINE. 



Mr. John B. Root exhibited diagrams of his new steam engine, 

 now on exhibition at the American Institute Fair, and explained its 

 construction as follows: 



"Figure 3 represents a vertical section, and Fig. 1, a perspective 

 view of the engine; the same letters referring to the same parts in 

 each. The cylinder, A, is cast with the exhaust chamber, P, run- 

 ning entirely around it; thus jacketing the cylinder with exhaust 

 steam and preventing the condensation that takes place in the ordi- 

 nary engine, where the cylinder is exposed to the atmosphere. The 

 steam chest, «7, and the lower cylinder head are also cast on the 

 cylinder. The trunk, D (shown in perspective in Fig. 4), passes 

 entirely through the cylinder and cylinder heads, and has a recip- 

 rocating motion given to it by the pressure of the steam alternately 

 upon the upper and under sides of the piston, C, which is cast on 

 the trunk. Within this trunk the connecting rod, E, swings, and 

 and is connected with it by the cross pin, W. The connecting rod 

 imparts motion to the shaft, F, by being connected with it by the 

 crank, G, and crank pin, H. The trunk is kept in line while recip- 

 rocating by the upper guide, B, cast on the upper cylinder head 

 and lower guide, B\ bolted on the lower cylinder head, thus 

 relieving the cylinder and piston from side wear. As the insides 

 and ends of the cylinder and guides, faces of cylinder heads, and 

 the outside of the. trunk and piston are all turned and fitted up in 

 a lathe, the piston must necessarily run true with the inside of the 

 cylinder, or, in other words, the centers of the cylinder, both 

 guides, trunk and piston, must always be in one line. Around the 

 edge of the piston, at a, and around the ends of the trunk, at b and 

 h\ in Fig. 4, are turned grooves, in which are inserted the steel 

 packing rings. Fig. 5, which rings being turned eccentrically with 

 the middle, at /, the thickest, and gradually tapering in thickness 



