This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Lead pipes will be most easily examined on delivery, when the ends of the coil will be stamped with some figures or letters to denote the weight per foot. After the pipe has been cut it will be next to impossible to tell if it is the right weight by appearance. All lead pipe which is not new should be rejected, as well as any showing unequal thickness. The running of lead pipes should be carefully watched and boards should always be put up, against or upon which the pipes may be securely fastened. Lead pipes which are run vertically should be fastened by hard metal "tacks", which are soldered to the pipe at intervals of about three feet. Unless this rigid fastening is done, the pipes will "crawl" and droop downward by alternate contraction and expansion. Horizontal pipes may be secured by bands but should have a continuous strip of wood to support the entire length, or they will in time sag down and form a hollow place, from which the water cannot be drawn when pipes must be emptied. The pipe should be made to rest upon the straight support and never be allowed to take an upward bend in its level course, as a bend of this kind will soon become filled with air and will eventually stop the flow of the water unless punctured at the highest point.
All the joints in lead pipes should be wiped joints as specified and no cup joints, which are more easily made, but not so strong, should be accepted. The joining of lead and iron pipes must be made by wiping to the end of the lead pipe a strong brass "ferrule" which can be caulked into the iron pipe. This will need to be looked out for as it is a great temptation to many plumbers to putty the lead pipe into the socket of the iron pipe.