362 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



In support of the view that steam may be applied to this kind of traffic, 

 we have, in the last number of the London Mec. Mag., an illustrated account 

 of the fifty-third traction engine built by Aveling & Porter, of Rochester. 

 In this engine there are some good points. The steam-jacketed cylinder is 

 in accordance with the practice of Watt, which has of late been revived, 

 and recommended, especially by D. K. Clark, the best authority on loco- 

 motive practice. The steering gear is simple and effective; I believe 

 Gurne}'' was the inventor of .t; it is shown in some engravings of his 

 carriages. But it is not applicable for high speed and flexible springs. 

 The whole arrangement, being without springs, is simple and cheap, but 

 of course it is too slow for city traffic; and, from observation of a well 

 built traction engine, I am of opinion that on soft roads a low rate of speed 

 will be found disadvajitageous, because there will not be sufficient momen- 

 tum to pass over soft places. 



I differ from Mr. Aveling, and from all the English traction engine 

 projectors, in regard to gearing. This engine is geared to make twentj' 

 turns to one turn of the wheels. Let us consider this. I have calculated 

 that the Great Britain locomotive, with eight-feet wheels, consumes five 

 per cent, of its power in sliding its valves. D. K. Clark estimates that six 

 per cent, is consumed in some locomotives, whose wheels, I presume, are 

 smaller; and his authority corroborates my estimate. Now, if we keep the 

 same boiler and the same speed on the rails, but use four-feet wheels, we 

 double the friction of the valves, and so on, until, when the wheel is reduced 

 to 4.6 inches diameter, the engine will barely slide its valves. Now, if, 

 instead of gearing, this traction engine had reduced its wheels, they must 

 have been 3.9 inches to get the same number of turns per mile that the 

 engines now make. But the speed is one-twentieth of that of the Great 

 Britain; hence the parts are smaller, and the valve smaller, and the friction 

 proportionabl}^ less, but still it is 6.15 per cent, of the gross power. If 

 four-feet wheels, with direct action, were used, the valve friction would 

 be .005 — one-half of one per cent, a saving of .0565 — or nearly 5| per cent, 

 of the gross power; and the loss of steam in the ways and clearances is 

 much greater than it would be in a large cylinder working slowly; and the 

 friction of piston, crosshead and gearing consumes a large per centage of 

 the power. Mr. John A. Reed, of this city, built an engine, some years 

 ago, in which some complex gearing was used; and when he removed it, 

 the engine could draw more, although the engines made fewer turns per 

 mi-le. 



I hold that it is best to use wheels of moderate size, with direct con- 

 iie."!tion — that is, a turn of the wheels to each turn of the engines. There 

 is but one objection to this — the loss of heat from the cylinders. But I 

 design to jacket the cylinders, and to lag the jackets, and in some cases to 

 put the cylinders close to or within the smoke-box; in this way I believe I 

 can avoid much loss of power from condensation. 



In another point I differ from them. Instead of spikes, spuds and other 

 contrivances to get adhesion, I put as much as I can of the drawn load 

 upon the drivers, making their rims broad enough to bear whatever weight 

 is necessary for adhesion with smooth tires. 



Here is a drawing representing a two-wheeled pleasure carriage, con- 



