MEANS OF COMMUNICATION. 31 
arrangement permits the wheels to accommodate themselves to the curves 
of the track, without reference to the main body of the carriage. 
In order to arrest the cars when it is necessary to stop, or to check their 
progress in descending inclinations upon the road, brakes become necessary ; 
they consist of blocks of wood which are pressed against the rim of the 
wheels by an arrangement of levers, or in any other manner, and thus produce 
sufficient friction to arrest or at least to retard the motion of the cars. The 
simplest form of brake is seen in pl. 5, fig. 22; the lever, 6, is so connected 
with the brake block, c, that when the lever is depressed the block is 
pressed against the wheel, but when the lever is raised to the position 
indicated by the dotted lines the block is removed from contact with the 
wheel, which is left free to revolve. 
A brake of different construction is seen in jig. 9, in which motion is 
communicated to the brake blocks ff by the lever g, through the joints cd, 
the one being pressed forwards and the other backwards. In this manner 
by a slight modification all the brakes of a six or eight-wheeled car may be 
applied at once; in jig. 27 is seen a brake of this description. /%g.19 shows 
a brake of different construction; 4% are the brake blocks, secured to the 
rack bars 2%, which engage with a cog-wheel upon the upright axle /; 
upon this axle there is a bevel wheel, which gears with a similar bevel 
wheel upon the shaft 7, which is in a similar manner connected with the 
crank ¢ above, and thus upon turning the crank the brakes are applied to 
the wheels, the one forwards and the other backwards. In this same 
figure is seen a peculiar method of applying springs to buffers. The buffer- 
rod @ is attached to the bent lever 0, one arm of which is connected with 
the spring d, through the rod c. When two cars strike together, the rod a 
is forced in, and by means of the bent lever and connecting-rod the force 
of the blow is transmitted to the spring d, which thus neutralizes the shock 
and returns the buffer to its place when the pressure is removed. 
In order to connect several cars into one train, coupling bars or chains 
become necessary; sometimes these are attached immediately to the car 
frames, at others to springs upon the frame as in pl. 5, fig. 26; the coupling- 
chain is hooked into the hole / upon the end of the bar d, which is attached 
to the small pair of semi-elliptical springs which afford a certain degree of 
elasticity to the connexions, and prevent the disagreeable jars which are 
experienced in starting and stopping where the couplings are rigid. Some- 
times the chain-couplings are drawn together by means of screws until the 
buffers touch, in order in passenger cars to diminish the unpleasant jolting 
of the cars against each other; at the short turns in the road this arrange- 
ment, however, has a tendency in conjunction with the centrifugal force to 
throw the cars off the track, or at least by increasing the friction to injure 
the roads, cars, and locomotives. A plan of this coupling is given in 
pl. 5, fig. 20, and a side view in jig. 21; aa are the coupling-chains 
attached to the end hooks of the car at d; the buffers } are brought in con- 
tact and the arm ¢, attached to a right and left screw, is turned until the semi- 
elliptic springs (jig. 26) are slightly strained, and the lever is suffered to fall 
into a vertical position, the weight w upon its end keeping it from rising. 
611 
