Porcelain vs. Glass

PORCELAIN INSULATORS FOR OVERHEAD LINES

The appeal to porcelain manufacturers, made in our columns last week, by Mr. F. W. Jones, the electrician of the Postal Telegraph-Cable Co., touches a very important part of telegraph and telephone construction work. As Mr. Jones pointed out, although porcelain insulators are given the preference in Europe and are found to present three or four times the resistance to leakage that glass does, our companies continue to use glass, in spite of the great loss of efficiency in service. It would in fact be interesting to know just what becomes of the various classes of telegraph circuits under heavy conditions of rain and damp. Our own impression is that a seriously large proportion of them is "shut down" until fine weather comes around again, and that this is chiefly due to the poor character of the insulation at the poles. We doubt whether in this respect there is any material gain over the efficiency of twenty-five years ago.

Mr. Jones by his appeal to the porcelain manufacturers of America has assumed that with them rests the remedy, and that if they will give us porcelain insulators cheap enough and good enough, all will be well. On these points we have now been favored by Mr. C. H. L. Smith, of the Union Porcelain Works, of Brooklyn, with copies of a very interesting correspondence between himself and Mr. Jones, and the data thus submitted is important. Mr. Smith remarks in a letter to us, with great truth and pertinence, that the question of the most perfect insulation obtainable will before long be well recognized by those who use electric plants of any kind as one of the prime factors in reducing operating expenses, but he seems to fear that for the present the short-sighted policy will prevail of looking only at the first cost of the equipment. In one of his letters to Mr. Jones, he says but too truly: "The managers of European lines look at other points than the first cost of their insulators. Unfortunately in our country, in too many cases, quality is sacrificed to price, and the first, and sometimes the only, element that cuts any figure in transactions is, "What is the price?" The glass telegraph insulator being much less costly than the porcelain, our electricians as a rule have very little option in the matter. They are compelled to work with such tools and equipment as the management provide for them." In other words, the tariff plays little part in the matter, and there is no need to consider importation, if the companies interested will only buy what they can already get. Has any determination been arrived at, we would ask, as to the exact point at which the loss of efficiency and business on our telegraph lines, from poor insulation, would be less or greater than the added outlay required for high-class insulators?

As to the porcelain itself, Mr. Smith is worth quoting:

"The insulating properties of porcelain depend upon its quality. You are no doubt aware that there are many goods manufactured that have somewhat the general appearance of porcelain but in reality are not true porcelain. Such inferior goods do not make a hard porcelain such as we manufacture is identical with the class of insulators used in Germany and France, and is a superior insulator to that used in England."

"In regard to the glaze of true hard porcelain, it does not better the insulator one particle. The body of the true porcelain is as perfect an insulator as the glaze. The only objection to omitting the glaze is that the surface of the body becomes more quickly and readily soiled. We have thoroughly and carefully investigated this whole matter, and the only point that interferes with the general use of a porcelain telegraph insulator, which is an item only in first cost."

This last sentence is plainspoken, although it deserves to be borne in mind that the question of renewals comes in. We believe that about 6 per cent. of the Western Union insulators are renewed yearly. But there again, however, there might be an economy in a smaller percentage of renewals.

In another letter to Mr. Jones, objection is made by Mr. Smith that the former's requirements do not go quite far enough, and that

"A high-grade porcelain insulator should be composed of simple earths only, both in body and glaze, and of the same material. No lead or other metallic oxides must enter the composition of either glaze or body. It must be absolutely vitreous and perfectly homogeneous. The body and glaze must be fused together at the highest porcelain heat, which is over 4,000 degrees Fah. It must be resistant to all influences of heat, cold, dampness, acid or alkali fluids or gases."

With the need so well recognized and with the ability to supply it so well manifested, there should be little delay on the part of porcelain manufacturers in this country in finding a new market in the telegraph field.