MECHANICS AND USEFUL ARTS. 19 



be drawn out by forging, so as to form projecting pieces at those parts 

 of the circumference where the spokes are to be welded on. There 

 must necessarily always be an even number of spokes, so placed upon 

 the half-naves that those of the one half shall come into the spaces be- 

 tween those of the other half. The projections or flanges having been 

 drawn out, the spokes are to be welded on, each one having a portion 

 of the felloe welded thereon, the alternate portions being on the half- 

 naves respectively. The halves are to be brought to a welding heat, 

 and then welded together by a suitable hammer or press ; after which 

 the centre of the nave is to be cut out to receive the axletree. Civil 

 Engineer and Architect's Journal, June. 



AUTOMATIC REGISTER OF THE SPEED AND OF THE TIME OF 

 STOPPING OF RAILROAD TRAINS. 



UNDER this name, M. Breguet submitted to the French Academy, 

 on Dec. 17, 1849, an instrument intended to exhibit the speed of 

 trains on railways at all points, as well as the time passed at each 

 station where the train stops. His machine consists of three parts ; 

 a clock-work wheel, one of whose axles bears a "helix curve," 

 which revolves in an hour, or in any fraction of an hour ; this helix 

 causes a pencil to move perpendicularly from below upwards ; a paper 

 band of any length ; an endless screw, whose axle carries a pulley at 

 its outer extremity. This screw gives motion to a wheel, the pinion 

 of which tooths into a second wheel, mounted upon an axle, which 

 carries a cylinder designed to move a band of paper. The machine 

 being placed upon the tender, or upon a car, a pulley is put upon one 

 of the axles of the wheels, and, a cord being passed over this pulley, 

 as well as over that of the machine, the screw will turn, if the car 

 moves, and the wheels and the cylinder, and consequently the band 

 of paper, will be set in motion. Thus there are two distinct motions, 

 independent of each other, the one horizontal and variable (that of the 

 paper band), and the other vertical and uniform (that of the pencil). 

 By means of these two movements we have a winding curve, the ab- 

 scissas of which represent the space passed over, and the ordinates the 

 time passed. In. the machine exhibited, the relation between the 

 cylinder and the pulley is 5 y, the diameter of the cylinder 6 centi- 

 metres ; consequently 300 revolutions of the pulley will represent an 

 unrolling of the paper of 20 centimetres, and if the 300 revolutions 

 are caused by a train in going 1 kilometre, it is evident that each centi- 

 metre of paper will present a space passed over equal to 50 metres. 

 The breadth of the paper is 6 centimetres ; if the crayon passes over 

 it in twenty minutes, each minute will be measured by a distance of 3 

 millimetres. It will be readily perceived that curves traced in this 

 way would give all the variations in the speed of the train. 



THE " NOVA MOTIVE. 



A NEW mode of propulsion is being demonstrated at the Polytechnic 

 Institution, consisting of a series of carriages, carrying alon? with 



./ O O 



