Their
use arises from the greater convenience of moving the smaller pipes.
They are generally 11 and 15 inches in diameter. It is recommended,
however, in order to prevent a loss of head, to continue the branch
pipes of the same size as the feed pipe, and to regulate the discharge
by the size of the nozzles. At the Southern Gross and Polar Star Mines
the supply pipes at the pressure box are 40 inches and 48 inches
(respectively) in diameter, tapering for 500 feet to 22 inches, which
size they retain for 2,800 feet, then branching into two pipes each of
15 inches. At the Malakoff the pipe at the head is 27 inches, narrow-
