Trade by Major Cardew reapesting certain The report presented to the Buad of
defects which have developed in the system of bare copper mains employed by the St. James's and Pall Mall Company, interesting record of tle vagaries that may be played even by the harmless low pressure current when the insulation of the conductors is imperfect. It appears from the report that in September last two explosions occurred, due to accumulations of gas and water respectively, a faulty pilot wire being the immediate cause of explosion of yas; and that tests, which were nade soon afterwards at the suggestion of Major Cardew, showed that there was a serious earth connection on the negative Mr. Hart wished it to be understood that main, the difference of potential between xbout 190 volts instead of 110 volts which it should have been if the two sides of the circuit had been equal in insulation, This earth connection seems to have Aetied the efforts of the Company to remove it, and continued to exist until ently in April, when it was removed during the Uuperations, consequent on the enquiry into tite cause of the damage done to a gas meter and to two water pipes, this damage being the subject of the present report by Major Cardew, The failure of a water pipe was first reported, and as it was stated that electric shocks were received on touching a tap in metallic connection with this pipe, and as the main of the London Electric 8 wear, the first An examination ed, however, that the high pressure main Was not at' fault, "s it was found to {be in very good order, and that no shook could be obtained from the outer casing and attention was therefore turned to the low pressure direct current mains, as it was thought that the damage done to the water pipe was very probably due to electrolytic action, At this time attention was drawn to the state of a gas moter, through the back of which two holes had been eaten at points where it was in contact with a damp wall, and as there were no signs of corrosion on any other part of the meter, its appearance seemed tu point again to electrolytic ae The next day it was reported that a water pipe had again failed, and when the geonnd was opened up to remove this pipe which passed under the electric culvert, a test was made, which showed that there was @ difference' of poial of about six volts between them, which was a sufficient explanation of the cause of the damag The culvert. was then opened, and was found to contain a good deal of water, and it was further discovered that some lead covered wires which had been used as pilot wires were badly fused, and that they were probably forming the connection between the culvert and the negative main. Major Cardew accounts for the action on the pipes by pointing out that the general insulation of the positive side of the circuit was vot high, and that the aggregate leakage current from the positive side first found its way to the gas and water pipes as the best earth, and then from them to the negatively charged culvert across the paths of least resistance, and that the electrolytic action of this current corroded the metal of, the
Text read from the printed page and cleaned; old type leaves the occasional error.