6o 4 POPULAR SCIENCE MONTHLY. 



power of the motor, which is located under the seat, is transmitted 

 through friction wheels. In looking at the illustration it will be noticed 

 that the hind wheels have a circular rim attached to the inner side, and 

 of a diameter somewhat smaller than the wheel itself. Two small 

 friction wheels are placed so that either one may be pressed against the 

 inner surface of this rim. The 'shape of the rim, as well as that of 

 the small wheels, is such that they hug each other firmly, so that the 

 rim is carried around in a direction which corresponds with the direction 

 of rotation of the friction wheel. In operating the carriage the motor 

 is set in motion, and then one or the other of the two friction wheels 

 is pressed against the rim on the driving wheel, according to whether 

 it is desired to run forward or backward. While this arrangement might 

 not operate with entire success if applied to a heavy vehicle, it appears 

 to be all that could be desired for a light carriage. 



Three-wheel vehicles have been used, but there is a difference of 

 opinion as to their value, as the construction has disadvantages as well 

 as advantages. It is evident that such a vehicle can be steered with 

 greater ease than one running on four wheels, but on country roads, 

 where the wagon wheels roll down a smooth surface, and leave the 

 space between in a rough condition, it is equally evident that the third 

 wheel, in passing over this uneven surface, would jolt the vehicle to a 

 considerable extent. On a smooth pavement the three-wheel vehicle 

 will run fully as well as the four-wheel; but, on the other hand, on such 

 a pavement the latter can be steered with as little effort as the former, 

 so that the question of superiority of design is one that probably de- 

 pends upon individual taste. 



From the descriptions of automobiles given in this and the two pre- 

 ceding articles, it will be seen that although many of them are used, 

 especially in France, they are not entirely free from objectionable 

 features. The electrical vehicles are provided with the most simple and 

 durable machinery, and, being noiseless, odorless and free from smoke, 

 are all that could be desired in so far as their operation is concerned; 

 but they are heavy and can only be used in places where the batteries 

 can be recharged. The steam vehicles are light, have simple mechan- 

 ism and can run anywhere; but they exhaust steam into the air, which 

 is clearly visible in cold or wet weather, and the heat from the engine 

 and boiler is an objection, at least in summer time. The gasoline 

 vehicles run well, but are noisy, and the odor of the gasoline is disagree- 

 able as well. 



