[Illustration: FIG. 15. JENATZY DOG-PHAETON.] American manufacturers of electric vehicles, at least the great majority of them, resort to spur-gearing to transmit the motion of the motor to the driving wheels, but with the French designers the chain and sprocket appears to be in great favor. Fig. 15 shows a Jenatzy vehicle (French), in which the chain is used. This construction would not be received with favor by Americans, who as a rule desire to have the mechanical part of the apparatus hidden from view as much as possible. In the Jenatzy vehicle two chain gears are used, one on each side of the body, and from the engineering point of view this is the most desirable arrangement, as with it the driving wheels are independently operated and a compensating gear need not be placed upon the axle. The American designer, however, would in most cases be controlled more by the artistic appearance and would use a single chain which would be placed under the body of the carriage, and thus as much out of sight as possible. Fig. 16 shows an English design of electric dog cart. The mechanism consists of a single motor which is connected with the axle by means of spur gearing, this being so arranged that several different speeds can be obtained for the vehicle with the same velocity for the motor. To obtain variable speeds by means of gearing it is necessary to introduce a considerable amount of complication, and in this country the opinion of most designers appears to be that the gain effected thereby is not sufficient to compensate for the increased complication, and differential speed gearing is not often used. [Illustration: FIG. 16. THE ELECTRIC MOTIVE POWER COMPANY’S DOG CART.] A comparison of Figs. 14 and 16 with 6 and 9 will clearly show that in so far as artistic effect is concerned, our manufacturers of electric vehicles have little to learn from Europeans, although the industry here is much younger than abroad. As to the operative merits, all that can be said is that the American carriages run so well and possess such endurance that it is probable that they are not second to any in these respects. THE HUMAN BODY AS AN ENGINE. BY PROFESSOR E. B. ROSA.