116 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[April, 



In all cases the same letters refer to the same parts : —a, in section 

 at Fig. 1, and in elevation at Fig. 2, is an inclined plane, over which 

 a friction roller, fixed to the engine, is intended to pass, and in so 

 doing, depress it to the level of the rail ; it is attached to the con- 

 necting rod c by means of the bell-crank 6 ; d\sa. rack fixed to the 

 rod c, giving a quarter turn to the disc i, through the pinion /, the 

 crank g, and the vertical shaft h\ ^ is a double crank fixed to the end 

 of the rod c, one arm of this crank carries the balance weight /, the 

 other arm lifts the piston r in the cylinders; by means of the con- 

 necting rod n, the lever m, and the vertical piston rod p, the upper 

 part of this rod communicates motion to the clock, shown to a larger 

 scale at Figs. 4 and 5, where ^ is the piston rod having a rack work- 

 ing into the teeth of the wheel q, upon the axis of which the fingers 

 of the clock are carried ; the cylinder s is open at the top, and has a 

 valve t opening inwards to admit air under the piston during its ascent, 

 and a stopcock u regulating the egress of the air from under the 

 piston, which, descending by its weight, drives the air out before it, 

 with a velocity proportioned to the area of the aperture, and thus by 

 opening or closing the stopcock, the time for the revolution of the 

 hands of the clock can be increased or diminished at pleasure ; the 

 piston, on descending to the bottom of the cylinder, lifts the catch e 

 out of the notch provided for it in the rod e, and releases the balance 

 weight I. 



Fdr the night signals, the clock, having a transparent white face, is 

 illuminated by the lamp and reflector z, Fig. 5 ; the vertical shaft h, 



which carries the day signal i, also carries a disc of red glass, y, fixed 

 within the lamp, and between the clock face and the light, and also in 

 the same vertical plane as the day disc; consequently, when the 

 quarter turn is given to the shaft h, the red glass is turned before the 

 light, and the clock face is illuminated red, and thus calls the attention 

 of the engine driver to the clock face. 



Mode of Action. — The inclined plane a, in descending, draws the 

 rod c forward, and lifts the weight^; the catch e descends into its 

 notch, and retains them in this position ; in the mean time the red 

 disc i has been turned by the rack d so as to be visible from the line, 

 the piston r has been lifted to the top of the cylinder, and descending 

 by its weight, communicates motion to the clock; on reaching the 

 bottom of the cylinder, it lifts up the catch e, which, rising out of the 

 notch in the rod c, releases the balance weight /, which, by its gravity, 

 brings the different parts of the apparatus into their first position, and 

 the signal is ready for the passage of another train. 



By these means the engine-driver, on passing the signal, and look- 

 ing at the clock, can tell by night or by day how many minutes have 

 elapsed since the passing of the previous train, and either stop until 

 the time for the revolution of the hand has expired, or regulate his 

 speed, according to his instructions. 



The only attention the signal requires is the cleaning and lighting 

 of the lamp, which might be done by one of the plate-layers, who are 

 always upon the road. 



TREWHITT'S PATENT FOR DISCONNECTING THE PADDLE-WHEELS OF STEAM VESSELS. 



gjjj Observing a notice in your Journal for February on "Trewhitt's patent method of disconnecting the Paddle-wheels of Steam Vessels," 



in which there are several inaccuracies, we beg the favour of your inserting the enclosed, which is a correct representation and description of 

 the apparatus applied by us to H.M. steamer Kite. 



Engine Manufactory, New Road, 

 Feb. 11, 1S42. 



We are. Sir, 



Your obedient Servants, 



BRAITHWAITE, MlLNER & Co. 



Front view and section of crank. 



Side view. 



Explanation of the Drawing. 



A. The Paddle Shaft. B. A east iron Disc keyed thereon. C. A wrought iron Strap surrounding the DUc,Jined with brass 

 Cushion. E. A tightening key for producing friction, by bringing the Cushion in contact with the Disc, 

 iron Strap, excepting that portion occupied by the Cushion. ///. Screws by which the brass lining is held to the Strap. 



A few blows of a hammer on the key E will connect or disconnect the Paddle-shaft, even when the engines are at full speed 



D.- A brass 

 F. The brass lining the wrought 



