Glass for Electrical uses

GLASS FOR ELECTRICAL WORK.

BY

A very interesting book on "The Glass Industry of the Last Twenty Years,"¹ by L. Appert and J. Henrivaux recently published in Paris contains some facts which should command the attention of those electrical engineers who look toward the future.

The book points to a long list of achievements which not only indicate something of the genius and enterprise of the present generation of glass experts, but which give us reason to hope for very great developments of this industry. Electrical engineering has much to gain by improvements in glass and some of the processes described in this book are worthy of prompt consideration by the electrical profession. Heretofore, the use of glass in electrical work has been confined chiefly to telegraph insulators, incandescent lamps and battery jars, but now we are confronted with the possibility of extending its use to subway tubes, manholes, lamp posts, large storage battery tanks, switch boards, the walls, floors and roofs of electric light stations and possibly to the tubular tunnels for underground railways.

These things have been made possible by the cheapening of glass itself, the improved furnaces for melting it in great quantities and by improved methods of molding it. The old way of making glass was in small crucibles; now it is made in immense tank shaped furnaces, some of them 100 feet long by 30 wide by 10 feet deep and no limit to the size that they may reach. The raw materials are put in one end, and the glass comes out at the other. It is continually flowing and never allowed to cool from year to year. Glass ware with the exception of plates cast on flat tables was formerly all either blown or pressed and it was impossible to blow a very large object, and more difficult to press it; but M. Appert has developed a method of molding it which is applicable to objects of any size and a great French firm are now placing on the market bath tubs, sanitary pipe, etc., and storage battery jars made under his patents.

Certain features of his molding method make the more perfect annealing of glass possible and it is marvelous to see the great strength possessed by a piece of heavy glass pipe well annealed. Of course, when glass pipes are mentioned, the question of good joints at once arises, but it is needless to say that Mr. Appert has taken good care of that problem, and that an entire system of subway construction has already been developed by him. The cost of such pipe need not exceed that of iron and its advantages are particularly apparent in these days when so many corrosive influences are present underground.

Storage battery work may also be benefitted by the ability to obtain heavy glass jars of great dimensions, and almost any engineer may think of some place where he could readily use a large glass tube or a heavy vessel with the qualities of glass. There is nothing else in the world so durable, so clean, so good for insulation, not to speak of transparency and resistance to action of acids. One has only to see some of the slabs of polished plate glass, 40 feet square made at St. Gobains to realize the beauty of glass as a material and if there is to be another age after the wooden age and iron age are past, it will probably be the glass age.

It is true that among the lost arts some of the results of Persian enameling have not altogether been reproduced, but a glance at this book will convince those most prejudiced against glass that we have entered upon an era of rapid progress in the application of a material which has long been deftly used but little understood and comparatively little appreciated.

The book describes methods of soldering glass to metals and tells something about lenses for projectors which is interesting to electrical engineers, but it tells a good deal more that will catch the popular mind. It gives some drawings of a complete glass dwelling house and a design of a glass portiere and has some chapters on art glass, also on glass smoke stacks, glass tables, wine tubs and many other things, besides much interesting technical information.

¹ "La Verrerie depuls Vingt Ans." Paris, E. Bernard & Co.