boiler, and of which the purpose is to regulate the admission of the steam
to the cylinder; _f_ is a safety valve kept closed by springs; N is the
eduction pipe, or, as it is commonly termed in locomotives, the _blast
pipe_, by which the steam, escaping from the cylinder after the stroke has
been performed, is projected up the chimney H. The water in the boiler of
course covers the tubes and also the top of the furnace or fire box. It
will be understood that there are two engines in each locomotive, though,
from the figure being given in section, only one engine can be shown. The
cylinders of this engine are each 14 inches diameter; the length of the
stroke of the piston is 21 inches. There are two sets of driving wheels, 5
feet diameter, with outside connections.

[Illustration: Fig. 29.]

132. _Q._--What is the tender of a locomotive?

_A._--It is a carriage attached to the locomotive, of which the purpose is
to contain coke for feeding the furnace, and water for replenishing the
boiler.

133. _Q._--Can you give examples of modern locomotives?

[Illustration: Fig. 30.]

[Illustration: Fig. 31.]

_A._--The most recent locomotives resemble in their material features the
locomotive represented in fig. 29. I can, however, give examples of some of
the most powerful engines of recent construction. Fig. 30 represents
Gooch's express engine, adapted for the wide gauge of the Great Western