e heavier
stamps, 9 cwt. and even heavier.

To find the horse-power required to drive a battery, multiply the weight
of one stamp by the number of stamps in the battery; the height of lift
in feet by the number of lifts per minute; add one-third of the product
for friction, and the result will be the number of feet-lbs. per minute;
divide this by 33,000 which is the number of feet-lbs. per minute equal
to 1 h.-p. and the result will be the h.-p. required. Thus if a stamp
weighs 800 lb. and you have five in the box, and each stamp has a lift
of 9 in. = 0.75 ft. and strikes 80 blows per minute, then 800 x 5 x 0.75
x 80 = 240,000; one-third of 240,000 = 80,000 which added to 240,000
= 320,000; and 320,000 divided by 33,000 = 9.7 h.-p. or 1.9 h.-p. each
stamp.

The total weight of a battery, including stamper box, stampers, etc.,
may be roughly estimated at about 1 ton per stamp. Medium weight
stampers, including shank cam, disc, head, and shoe, weigh from 600 to
700 lb., and need about 3/4 h.-p. to work them.

The quantity of water required for the effective treatment of
gold-bearing rock in a stamper battery varies according to the
composition of the material to be operated upon, but generally it is
more than the inexperienced believe. For instance, "mullocky" lode
stuff, containing much clayey matter or material carrying a large
percentage of heavy metal, such as titanic iron or metallic sulphides,
will need a larger quantity of water per stamp than clean quartz. A fair
average quantity would be 750 to 1000 gallons per hour for each box of
five stamps. In general practice I have seldom found 1000 gallons per
hour more than sufficient.

As to the most effective mesh for the screen or grating no definite
rule can be given, as that depends so largely on the size of the gold
particles contained in the gangue. The finer the particles the closer
must be the mesh, and nothing but careful experiment will enable the
battery manager to decide this most important point. The American
slotted screens are best; they wear better than the punched gratings and
can be used of finer gauge. Woven steel wire gauze is employed with good
effect in some mills where especially fine trituration is required. This
class of screen requires special care as it is somewhat fragile, but
with intelligent treatment does good work.

The fall or inclination of the tables, both copper and blanket strakes,
is also regulated by the class of ore. If it sh