Jurington.] HYDRAULIC MINING. 129 
ping made-up pipe of different diameters which renders it secure from 
bending or injury in transport. The iron bolt can afterwards be used 
in the blacksmith shop. 
Pipe made up beforehand is coated by immersing it in a bath of 
asphaltum preparation. This is highly important, and if the operator 
rivets his pipe on the ground he should dip the pipe in such a bath 
before laying. Bowie gives the following formula for a bath: 
Per cent. 
Crude asphaltum 28 
Coal tar ( free from oily substances) 72 
The advantages of using sheet steel, commonly called " hydraulic" 
pipe, are its cheapness of construction, adaptability for crossing 
depressions (as in inverted siphons), the facility with which its position 
can be changed, and, when slip joints are used, the ease with which the 
line can be laid. Many engineers do not recommend the use of slip 
joints — that is, the slipping of the end of one length of pipe 3 inches 
into the end of the next to form the joint. With average tonography, 
wood cap 
^threaded iron rod\ / ! ,• \ » \ 
'- -- !7fT. H 
Fig. 22. — Method of nesting made-up hydraulic pipe for shipment. 
however, experience has proved that such joints stand great pressure, 
and the practice is nearly universal among hydraulic miners. 
Pipe is used for the three following purposes: 
(1) As a water conduit, replacing ditches and flumes. Pipe is not 
recommended for this purpose except where siphoning is necessary or 
where conditions are particularly difficult for ditching and fluming. 
(2) For leading water from the pressure box to the claim. 
(3) For leading the water from the gate of a Y to its various points 
of discharge, as to giants, elevators, and impulse or tw hurdy-gurdy " 
wheels. 
The discharge pipe is generally a nozzle, either manipulated by 
means of a swivel-jointed tapering pipe called a giant or monitor or 
fixed within a larger pipe (the contrivance known as an elevator), or 
acting on the buckets of a wheel. 
The thickness of the iron or steel employed is determined by the 
pressure of the water and the diameter of the pipe. Table 9 gives 
information concerning a few of the sizes used in Alaska. Prices are 
those prevailing in San Francisco. 
Bull. 263- 05 9 
