LOCOMOTIVE ENGINE. 
435 
each other, having a semicircular notch at the end fitted exactly to the cross head F, 
which is a turned iron pin, one inch and three-quarters in diameter. The cross head E 
is attached to the arms E E, of the socket B B, by wrought iron straps, G G, fitted 
on to both, and fixed by the keys and gibs H and /; the gibs being required to 
prevent the ends of the straps being sprung open by driving the keys. A small pro 
jection upon the cross head is fitted into a notch in one of the arms, D, in order to 
prevent its turning round. 
The ends of the cross head K K are inserted into two guide blocks, B B f 6 inches 
long and If inch thick, with flanches on the inner side ; these are made of steel and 
are grooved on the sides to save metal. Each of these guide blocks is placed be 
tween two steel bars, MN, inches wide, fixed firmly to the frame of the engine, 
and shewn at A' A', in Plates XC. and XCI. The guide blocks and bars are 
ground together and fitted accurately, enabling the blocks to slide steadily and easily 
between the bars; the upper bar, M, is five-eighths of an inch thick, and the 
lower one, TV", one inch thick in the middle, and five-eighths of an inch at the ends; 
the two being connected firmly ‘together by small pillars, c, (Plate XC.,) fixed 
into them at each end. The lower bar, N, is required to be stronger than the upper 
one, as it is only supported at the ends. The upper bar, M, is fixed to a piece of 
angle iron, 0, (fig. 19,) by bolts P, with countersunk heads, ground down flush 
with the bar; small pieces of brass, Q, being interposed between the bar and the 
angle iron at each of the bolts, affording the means of adjusting the bars accurately 
level when the angle iron O is fixed on to the engine framing B. The bars M N 
are adjusted exactly parallel to each other, and to the axis of the cylinder, so as to 
allow the blocks, Z/, to slide behind them without any strain when moved by the 
piston rod and cross head; and they serve the purpose of guiding the end of the 
piston rod, and causing it to move always exactly in the line of the axis of the 
cylinder. 
Connecting Rods.—The connecting rods B'B', (Plates XC. and XCI.,) are 
fixed at one end to the cross heads, and at the other end to cranks on the axle, C' C A , 
of the large wheels, D' D', of the engine ; they are of wrought iron, two inches 
diameter in the middle, and taper down to one inch and five-eighths towards the ends. 
The manner of fixing them to the cross heads, is shewn in figs. 17, 18, and 19, S 
being the end of the connecting rod, enlarged at TT to three inches wide, and made 
square and flat at the end. The brass bearing, U, is fitted to the end, and has 
another brass piece, V t upon it, made octagonal on the back; the two brasses are two 
inches wide, and have flanches upon them at the sides, as shewn by the dotted lines 
in fig. 18, that of the end brass V being semicircular. 
The brasses are fitted accurately on to a spherical ball, W, that is turned upon the