THERE are, of course, many patents on methods of preventing corrosion. Years ago, the principal cause of corrosion of underground metallic structures was the effect of stray d-c current from electric traction systems and, therefore, most of the earliest patents had to do with methods of operating the traction system to minimize stray currents or with interconnections between the underground structures and the traction system.
Patent No. 538,758 was issued to R. Watkins on May 7, 1895. It is entitled, “Preventing Electrolysis of Street Pipes.” It is described as, “a method of preventing electrolysis of metal street pipes located adjacent to electric railways, which consists of connecting the pipes to the return conductor or the generator, whereby the said pipes receive and conduct the surplus electricity, which would otherwise indirectly charge the earth adjacent to or surrounding the pipes, thereby preventing electrolytic action.” This apparently covered the drainage wire type...
