EXPLANATION OF THE PLATES. 403 



is intended to represent the base, the section being taken as looking into the cylinder 

 from the front. 



Fig. 3 shows a detached plan or horizontal view of the hollow axle and piston, 

 with the partition and two steam ways in dots. 



Fig. 4 represents a horizontal section of the above, taken through the centre of 

 the hollow axle, showing the exit steam way v complete, and the partition t in 

 section. 



Fig. 5 is a face view of the side of the piston, fitting against the internal peri- 

 phery of the cylinder ; and fig. 6 exhibits a plan view of one of the slides s, with 

 the tail piece h and roller g shown connected to it. This figure represents, in 

 section, the method of attaching the slide s to the tail piece h, which is done in the 

 following manner: on to the sunken part, 1, of the slide is cast a pin, 2, and over 

 this pin is placed a wrought iron piece or collar, fitting rather loosely, into which 

 the rod k is screwed, as shown in the plate. 



PLATE LXXIII. 



CONTRIVANCE FOR PREVENTING A LOCOMOTIVE ENGINE FROM RUNNING 

 OFF A RAILWAY. BY RICHARD AYRE, ESQ., NEWCASTLE-UPON-TYNE. 



This plate represents one of the ingenious contrivances of Mr. Ayre. 



The figures 1, 2, 3, are different views of the locomotive engine, with the 

 necessary apparatus. In fig. 1, A A A, represents a steel bar descending below 

 the rail in the inside, about an inch below the flange of the wheel. This bar is 

 connected to the frame of the engine by a joint, B, about which it is moveable ; and 

 a roller, E, is attached at the bottom, and a cross bar or brake, G, at the top. It 

 is also connected with the steam valve by means of the chain H H ; C is a joint 

 to enable the bar to move backward or forward ; D is a spring connected to the 

 frame of the engine and, by the chain ED, to the bar A A A, which spring would 

 be pulled down were any thing to come in contact with the bottom of the bar 

 A A A, in the line of railway, and enable the end of the bar to move back and 

 relieve itself. Also FF are two springs to keep the cross bar from the side of the 

 engine, as shown in the cross sections fig. 2 and fig. 3. 



Should there be any tendency to run off the railway, the bottom of the bar 

 A A A, would by the pressure against the rail be driven inwards, and by its action 

 round the joint B, the brake G would be caused to press against the wheels, and 

 thus by the corresponding friction stop the motion ; and at the same time this 



