Glass Conduits

A GLASS CONDUIT.

For the n—th time (in a formula where N stands for infinity), glass has again come to the surface as an insulator for underground work. When we old people were young, and electricity was in its swaddling clothes, we were taught that glass was one of the very best insulators known; and we can all remember, if we stop to think, how the good old professor in gold-bowed spectacles carefully polished up the leyden jars, to make them bold the charge of electricity which the wheezy and rickety cylinder machine evolved, if it was a tolerable dry and cold day.

One cannot remember everything, and the most important part of a scientific showing, or the nub of a joke is often forgotten, while the balance is indelibly impressed on the tablets of memory. Every one remembers that glass is a non-conductor, but nearly everyone forgets that it is hygrometical, and never tires of accumulating water on its surface by condensation.

A doctor somewhere in Pennsylvania has invented a method of underground conduit, in which the wires (telegraph and telephone) are laid in grooved plates of glass, the interstices filled with pitch, laid up like layers of jelly cake, until you have as many in as you need. The whole is then placed in a long coffin, and the latter is buried in cement. There are no religious services; these come later, when the wires give out, and the council refuses to allow the company to disinter the corpse. At intervals of twenty-five feet or so each wire is brought out through a right angle groove in the glass, so that an inch and a half of the wire is exposed, for cutting and testing. The immense value of the invention can only be appreciated by those who have had experience with wires in this preserved condition, and to know from the reporter that ''the results of twenty years' experiments with electricity are embodied in this device," and "the convenience of this plan of connecting is greatly increased by the accurate registry of the wires which the discarding of all coils facilitates." This is a case where the sermon precedes the text.