Mr. Charles H. Morse, Inspector of Wires for the City of Cambridge, addressed the Engineering Society last evening on the subject: "The Operation of Electric Wires in the Streets of a Large City."
It is probably, Mr. Morse said, only a question of a few years before the large majority of the overhead wires in our large cities will be placed under ground, even including the trolley-wire itself. Experiments have already been made, which show that cars can be run equally well with the trolley-wire under ground.
It is necessary for every one who intends to become a mechanical or civil engineer to have a good fundamental knowledge of electrical engineering. These three professions are closely connected and work side by side. It has often happened that an engineer in one of these has been led into serious difficulties by his ignorance of the principles which govern the others.
In the city of Cambridge there are about 2500 miles of overhead wires, and somewhat over 800 miles of underground wires. Many of these are very heavily charged with electric currents of high tension. The are light wires and the electric car feeders have the highest tension and are exceedingly dangerous. It is often thought that a shock can not be received from a single wire, but this is a mistake, for the gound is thoroughly charged with the current from the underground wires, and when contact is made with the overhead wire by a person standing on the ground the circuit is joined and a shock is received. Rubber overshoes or gloves are seldom sufficient protection. Water is a very great conductor of electricity, and on a rainy day metal objects in the vicinity of heavily charged wires have often become charged themselves. This was well illustrated a year or two ago, when the iron railing around the grave yard at the corner of North avenue and Garden street became charged with electricity, so that every one who touched it received a shock. The remarkable power of water as a conducting agent was shown in the case of a man who was knocked down by a shock received in throwing water from a tin pail upon a burning block of a dynamo.
The West End road has three power stations, one at Allston, another in Boston, and a third in East Cambridge. This arrangement has been found far more expensive than it would be to have several more stations, and the power proportionately lessened. The current from these power houses is poured out through the feeders and returns through the ground, but this arrangement is very unsatisfactory, for the wear on the water and gas pipes, which carry the current, is very great, and pipes, which ought to last forty years often become worthless after three or four months' use.
After the lecture Mr. Morse remained for some for some time to answer any question which the members wished to ask him.