12. Q. What should be the position of throttle while drifting?

A. The throttle valve should be kept slightly open while drifting, so as
to admit a small quantity of steam in valve chamber and cylinder above
atmospheric pressure, to prevent the inrush of hot air and gases which
destroy lubrication, also to prevent excessive wear to valve, cylinder
and piston rod packing.

13. Q. How should the water be carried in boiler of superheater
locomotives?

A. As low as the conditions will permit, because this practice reduces
the tendency to work water over into the dry pipe and units, as the
superheater locomotive will use one-third less water than the saturated
locomotive.

14. Q. What care should be exercised in lubricating a superheater
locomotive?

A. The supply of oil to steam chest should be watched very closely by
the engineer, he to know that lubricator is feeding constantly and
evenly over entire division, and according to work performed.

15. Q. Describe the general form of a locomotive boiler.

A. A locomotive boiler is cylindrical in form, it usually has a
rectangular shaped fire-box at one end and a smoke-box at the other, and
flues extend through the cylindrical part, and, like the fire-box, are
surrounded by water.