Practical Rules for the Management of a Locomotive Engine:

In other circumstances, provided the fire is low enough to require fuel, the best time to put on coke is when the water is sufficiently high to turn off the feed-pumps, the steam slightly blowing off, and the Engine travelling at a good speed.

No definite instructions can be given for the frequency with which coke must be laid on the fire, as it varies according to the duty to be done, and the water consequently to be evaporated: in cases of heavy duty and bad gradients, it may at times be necessary even at as short an interval as 2 miles; under contrary circumstances an Engine may sometimes run as much