The above table is based on a steam pressure of 45 to 50 pounds per square inch of steam piston, and the vertical height is from lower end of suction pipe to discharge.
Fig. [438] is designed to show a pump largely used by miners in prospecting. It is double levered so that four men or more can operate it, two to each lever. The plunger and valves are so designed that they will lift muddy or gritty water without injury to these parts.
An electric mining pump is shown on page 276, part one. This is a portable pump mounted on a car running on rails and is designed for the work appertaining to a mine in steady operation.
On page 340, part one, is illustrated a powerful pump with four outside packed plungers designed for mining purposes.
SINKING PUMPS.
These special mining pumps are used to drain water from the shaft bottom, so that work in deepening or repairing may be carried on. As shown in the illustration they are made to be suspended by a chain or bail attached to eye-bolts in the upper cylinder head at points of support which will enable the pump to hang vertically and be raised and lowered at will.
Fig. 439.
The bail is so constructed that while the pump is suspended the cylinder head can, if necessary on the smaller sizes, be removed and the steam piston examined and adjusted. As the shaft gets deeper the chain may be lengthened out and an extra joint placed on the end of the delivery pipe.