MECHANICS AND USEFOL ARTS. 23 



above the level of the sea. The length of the road is two miles 

 and thirteen-sixteenths. 



The heaviest grade is 13 inches to the yard, and the very- 

 lightest, one inch to the foot. A part of the course is over "Ja- 

 cob's Ladder," the zigzag portion of the old bridle-path lying 

 just above the point where the trees are left behind. The rail- 

 road takes a generally straight line, however, curving slightly, 

 only to maintain a direct course. 



The locomotive pushes the car before it up the incline, and 

 both run upon three rails, the centre one being a cog rail. The 

 engine and car are kept upon the track by friction rollers under 

 tlie side of the cog rail, and the appliances for stopping the de- 

 scent are ample. By means of atmospheric brakes either the car 

 or engine could be sent down alone at any given rate, fast or 

 slow, and there are also hand brakes operating with equal direct- 

 ness upon the central wheels, together with other means of gov- 

 erning the machiner}' of locomotion. Every competent person 

 who has examined the road and the running machinery pro- 

 nounces both as safe as they could possibly be made. The land- 

 ing-place at the top of the mountain is directly in the rear of the 

 telegraph office, and but a few rods from the door of the Tip-Top 

 House. 



ELECTRICITY AND RAILROADS. 



On the railroads in France electricity is taking the place of hu- 

 man watchfulness. On many lines there are contrivances where 

 the passing of a train is automatically announced to neighboring 

 stations. The cars pass over connecting wires, and the train 

 records itself before and behind, so that its progress and appear- 

 ance are alike indicated. 



WHY DO RAILWAY CARRIAGES OSCILLATE? 



There is so prevalent an idea that the unpleasant, and, to the 

 nervous, injurious oscillation of railway coaches is due to the 

 axles being too wide for the line, that the following explanation 

 given in the " Times," by Mr. Charles Fox, is of much importance, 

 both to the public and the " companies : " — 



*' The oscillation of railway trains, more especially at high ve- 

 locities, producing what is ordinarily called ' gauge concussion,' 

 is a very serious source of wear to the permanent way and rolling 

 stock of railways, and as a consequence, of great expense, to say 

 nothing of the discomfort it occasions to passengers, and is, in 

 my opinion, caused, in very great measure, by the use of wheels 

 the tir(\s of which are portions of cones instead of cylinders. 



" It is well known to engineers that the tires of railway-wheels 

 are generally coned to an inclination of one in 20. It is con- 

 sidered that these were first introduced by Mr. George Stephen- 

 son, in the expectation of facilitating the passage of vehicles 

 round curves, by their adapting themselves, through their various 



