in cast-iron pipe in such a manner that the resistance is practically _nil_; and as for wrought iron or steel, the joint resistance may be made as low as we please by fitting the surfaces so carefully that white-leading is unnecessary. Arguing from the fact that the negative electrode is not attacked, it has been suggested to employ an auxiliary dynamo and a special system of wiring, in order to maintain the pipes, etc., at all times and at all points, negative to the rails. Could this ideal condition be realized, the rails alone would suffer. We can not hope, however, to thus easily solve the problem in towns where the distribution of buried conductors is at all complex. [Illustration: LEAD SERVICE PIPE SHOWING THE IRREGULARITY OF ELECTROLYTIC ACTION, OR WHAT IS TECHNICALLY KNOWN AS “PITTING.”] It has been suggested, also, to discourage the flow of electricity along pipes and cable covers by inserting insulating sections of wood or terra cotta. This plan has never been tried on a scale large enough to afford a suitable demonstration of its utility. While it might reasonably be tried on new construction, its application to old work is almost prohibited by the attendant expense. [Illustration: LEAD SERVICE PIPE ILLUSTRATING THE LOCAL EFFECTS OF EIGHT MONTHS’ ELECTROLYSIS. The other side of this pipe is smooth and clean.] Attacking the problem from a directly opposite standpoint, there seems to be a chance of successfully invoking the aid of some purely chemical method of rendering lead and iron innocuous, electrolytically speaking. If we can obtain an insulating oxide, lacquer, or varnish that will retain its high-resistance properties during the ordinary lifetime of the buried metal, it will be possible to effectually protect pipes and cable coverings by coating them prior to burial. Or, if we can stumble upon an electrolysis-proof alloy, formed by the addition of a few per cent of some foreign metal to the pipe material during manufacture, the buried conductor will need no protection whatever. But, supposing that we discover this lacquer or this alloy and by such means guard against damage to all new construction, how are we to care for the metals already buried? We can not dig them all up and paint them, neither can we attempt to replace them by the new alloy. I do not see that the state of the art to-day presents any solution of the difficulty, other than the banishment of the single trolley system. None of the electrical remedies (so called) offers more than partial and temporary relief, and the chemical field is just beginning to be explored.