on the tender for carrying the petroleum, having a capacity of about 3
tons. But to have a separate tank on the tender, even though fixed in
place, would be a source of danger from the possibility of its moving
forward in case of collision. It was therefore decided, as soon as
petroleum firing was permanently introduced, to place the tank for fuel in
the tender between the two side compartments of the water tank, utilizing
the original coal space. For a six-wheeled locomotive the capacity of the
tank is 3-1/2 tons of oil--a quantity sufficient for 250 miles, with a
train of 480 tons gross exclusive of engine and tender. In charging the
tender tank with petroleum, it is of great importance to have strainers of
wire cloth in the manhole of two different meshes, the outer one having
openings, say, of 1/4 in., the inner, say 1/8 in.; these strainers are
occasionally taken out and cleaned. If care be taken to prevent any solid
particles from entering with the petroleum, no fouling of the spray
injector is likely to occur; and even if an obstruction should arise, the
obstacle being of small size can easily be blown through by screwing back
the steam cone in the spray injector far enough to let the solid particles
pass and be blown out into the fire-box by the steam. This expedient is
easily resorted to even when running; and no more inconvenience arises
than an extra puff of dense smoke for a moment, in consequence of the
sudden admission of too much fuel. Besides the two strainers in the
manhole of the petroleum tank on the tender, there should be another
strainer at the outlet valve inside the tank, having a mesh of 1/3 in.
holes.

_Driving locomotives._--In lighting up, certain precise rules have to be
followed, in order to prevent explosion of any gas that may have
accumulated in the fire box. Such explosions do often take place through
negligence; but they amount simply to a puff of gas, driving smoke out
through the ash-pan dampers, without any disagreeably loud report. This is