To facilitate the work of installation it is necessary to have some one present at all times with authority to act for the plumbing contractor. This may be the journeyman doing the work on small jobs, or a special foreman on large installations; but whoever it may be should be vested with sufficient authority to act in the stead of the contractor in any of the ordinary problems which arise for consideration from time to time as the work progresses.

In the absence of a plumbing law to the contrary, or a clause in the specifications preventing such a course, the plumber, as soon as his work is completed, can cover it, thus concealing any defects from sight. To prevent such practice, a clause should be inserted in every specification stating that no work shall be concealed from sight until passed by the architect, his representative or whoever has charge of the work.