THE STEAM PIPES AND THE SUBWAYS.
UNLESS the steam heating company can be made to effectually stop the leakage from their pipes which has, especially of late, become such an unbearable public nuisance, it looks as if the use of the subways might have to be given up on the line of the steam pipes, at least temporarily or until some cable can be made which will withstand the intense heat caused in the conduits by the escaping steam. At a recent meeting of the Board of Electrical Control, Chief Engineer Kearney and Expert S. S. Wheeler, who had been investigating the subject, reported as follows :
The sole cause of the trouble is the heat caused by the escaping steam from the pipes. This brings the temperature of the conduits up to a point which none of the cables as ordinarily made for underground work can stand, and it is doubtful if any practical cable can be made which can stand the high temperature, and at the same time be waterproof. All of the substances used as insulation in making waterproof cables are organic compounds, which either melt or become soft at a high temperature, in which case they both deteriorate as insulators and run and drip off the wires as well, or they become charred or burned, and thus lose their insulating properties, and crumble or drop off the wires. In order to avoid all of these materials, which are rendered useless by the heat met with, we decided to inquire into the probable chances of a cable covered with some woven fabric, but left dry ; that is, not treated with any fusible substance, such as wax or rubber, relying upon a lead pipe covering to keep the water out. We found that precisely such a cable has been laid by the Metropolitan Telephone Company across Broadway at Ann streel,where a high degree of heat was met; but unfortunately this has not been put in use yet, and we are not able to get its results. The teiegraph company laid a similar cable about two years ago, which gave out, but the cotton had been treated with some substance which may have impaired it, and the lead covering was injured enough to admit water. These were the only two cases we could find of effort having been made to make cables which would stand this heat, but unfortunately neither is a criterion. The remedy is unquestionably with the steam heating company in stopping the leaks. The problem of making a cable to stand the heat is one of great difficulty, and uncertainty as to the results, if it is possible at all. The heat caused by the steam leakage on Broadway was so great at the time the cable spoken of was laid two years ago, that it expanded the brass pneumatic dispatch tubes of the Western Union Company, and crushed their ends against the brick junction boxes. A lead covering for cables will carry off some of the heat at first, and in some cases where the heating is temporary or local, such a covering will be sufficient protection.
The telephone company has also reported that its cables laid parallel with the steam pipes have been badly damaged by the heat, and the Western Union Telegraph Company, with the assertion that the subways are virtually untenable for the purpose of its business, has asked permission to stretch 250 wires in five cables overhead.