realized.

The pipe was manufactured and inspected under the above-mentioned
specifications.

_Pipe Joints_.--There was a question about the reliability of the lead
joint at 300 lb. The writer had a section of 12-in. pipe, with standard
joints containing 22 lb. of lead, laid and tested to 500 lb. without
sign of failure or leakage. The joints were caulked down 3/16 in. below
the face of the bell. Of 8,700 joints thus made in the field, not one has
blown out or failed. A few weeped slightly on top, and they were made
permanently tight by additional caulking. The present maximum pressure
is 278 lb. These joints are the standard joints specified by the New
England Water-Works Association. It should be borne in mind that there
is no water-hammer on this line. In 8,700 joints, 198,000 lb. of lead and
3,200 lb. of oakum were used, or 22.76 and 0.37 lb. per joint.

Leadite was tested in competition with lead, but it leaked at 100 lb.
and failed under a sustained pressure of 300 lb. It is a friable
material, and cannot be caulked successfully. Its principal ingredient
appears to be sulphur. The failure was by slow creeping out of the
joints. It is melted and poured, but not caulked. It has attractive
features for low pressures and for lines not subject to movement or
heavy jarring.

_Air-Cushions_.--To prevent water-hammer on the pumping main, all pumps
are provided with large air-chambers. In addition, and as the special
feature for absorbing the shock of pumping under high pressure through a
pipe 21 miles long, a large air-chamber in the form of a closed steel
cylinder, 5 ft. in diameter and 15 ft. long, is mounted on the pumping