was bored from the log. This was a mistake, for bored pipe has a rough
interior and a reduced capacity. The inspection and culling are
difficult and unsatisfactory, and imperfections readily apparent in a
stave frequently escape detection in bored pipe.

_Pipe Joints_.--The chamber and tenon of this pipe is an all-wood joint,
4 in. deep. An iron sleeve makes a better and stronger joint. It
compensates for any lack of initial tension in the banding over the
chamber of the wood joint, and secures full advantage of the swelling of
the wood. Cast iron is better than steel; it is more rigid, and its
granulated surface breaks up the smoothness of the wood surface swelling
against it. One objection to the cast-iron sleeve is that of cost, but
it adds 4 in. to the effective length of every section of pipe, as
compared with the wood joints. On the Pacific Coast, a banded wood-stave
sleeve is used with success.

_Coating_.--To preserve the banding from corrosion and the wood from
exterior decay, the pipe is thoroughly enveloped in refined asphalt
having a flow-point adjusted to the prevailing temperature during
shipment and laying. One grade can be used through a considerable range
of temperature. This coating endured a 2,000-mile shipment successfully.
Each piece was carefully inspected along the trench, and any break in
the coating was thoroughly painted with hot asphalt. Enough of the
latter came in barrels, with the pipe, from the factory.

The first 37 miles of this pipe has been in service for two years.
Recent inspections show the coating to be in excellent condition and the
steel underneath to be bright and clean. In some cases, where the
initial pressure and leaking between the staves of the dry pipe were
great, the escaping air and water lifted the coating into bubbles. At