January i, 1910.] 



THE INDIA RUBBER WORLD 



119 



India-Rubber in the Electrical Field. 



By Ira IV. Henry. 



THE story of progress in rubber insulation during the past 

 twenty years is practically the contemporaneous history 

 of electrical achievement. 



All forms of electrical energy, whether generated for lighting 

 or power, or the transmission of intelligence, depend upon the 

 insulated conductor to successfully accomplish their purposes. 

 Twenty years ago such brilliantly illuminated streets as are now 

 common, with swiftly moving electric cars, were practically un- 

 known even in the world's greatest cities. The telephone, the 

 office and household necessity of today, scarcely existed then on 

 a commercial scale. All these conveniences and many others that 

 electricity has supplied have been arrived at only by the use of 

 perfectly protected wire. 



The increase in the use of india-rubber as a material for insu- 

 lation purposes during the past twenty years is indicated by the 

 fact that at the beginning of that period there were only five 

 insulated wire companies in America, turning out a product of 

 under $3,000,000 annually, while today there are twenty or more 

 manufacturers in this field, with an output exceeding $25,000,000. 



In 1889 the avenues and streets of the great cities were dis- 

 figured by pole lines carrying a network of uninsulated wires 

 for telegraph and other purposes. It was a necessity in those 

 days, in order to transmit electric currents safely, to suspend 

 the wires on insulators as far above the street traffic as possible. 

 As the use of high tension currents increased, the danger of 

 coming in contact with these wires was augmented, and in many 

 cases where the wires were dislodged and fell to the street, there 

 were serious results to life and property. 



Burying the Street Wires. 



It was just twenty years ago that active steps were taken by 

 the officials of New York city to remove the unsightly and 

 dangerous' pole lines from the streets, and after many public 

 meetings an ordinance was passed requiring the removal of all 

 overhead wires in a certain section within a specified time. 



This order was followed by protests from the electrical com- 

 panies, and at a meeting held in the city hall prominent electrical 

 engineers asserted that it was impossible to furnish current of 

 sufficient voltage to light the streets on insulated wires placed 

 underground. 



At the same meeting representatives of two of the wire manu- 

 facturing companies signified their readiness to furnish and 

 guarantee rubber insulated cables that could be placed under- 

 ground and successfully accomplish the desired work. The elec- 

 tric companies having a large investment in overhead conductors, 

 were naturally skeptical, but one company operating in Harlem, 

 placed an order for rubber insulated cables that were laid in 

 One Hundred and Twenty-fifth street, and much to the surprise 

 of the protesting engineers these circuits were a success from 

 the day they were installed. 



The city authorities, now feeling assured of the right of their 

 position, ordered all pole lines and wires cut down in a specified 

 section, which for a period left the streets in darkness at night. 

 This drastic action compelled the electric companies to take 

 steps to fulfil their contracts with the city for lighting the streets, 

 and within two years over 600 miles of rubber insulated con- 

 ductors were in successful operation, in wire subways. 



The action of New York was quickly followed by other cities, 

 which of course was greatly to the benefit of the rubber wire 

 manufacturers. Their business increased so rapidly that it was 

 impossible to handle their orders, and capital, quickly seeing a 

 new field for investment, was not slow in starting additional 

 companies. With the increased business and new ideas entering 



the field, the method of insulating conductors was greatly 

 improved. 



Methods of Covering Wires. 



The first American companies followed the process introduced 

 by Messrs. Siemens Brothers, of England and Germany, for 

 applying rubber to an electric conductor. By this process two 

 strips of rubber were placed longitudinally so as to cover the 

 conducting wire. The whole was then drawn through semi- 

 circular grooves which, in firmly pressing the strips around the 

 conductor, caused them to unite at the edges (while the com- 

 pound was still warm and immediately after the strips had been 

 cut), and thus form a complete cylindrical casing for the con- 

 ductor. The spare rubber from each strip was at the same time 

 trimmed off at the sides by small circular cutters, close to the 

 rollers. This plan was a great improvement in some respects, as 

 it overcame the objection to unevenness of covering due to an 

 overlapping seam. 



When more than one covering was applied, to withstand high 

 voltages, the joining lines of the successive layers were placed 

 at right angles to each other. Difficulty was experienced by 

 some manufacturers in having the seams of the rubber strips 

 unite sufficiently to overcome dampness which might creep into 

 the conductor when the wires were placed underground or sub- 

 merged. This led to the starting of the second school of insula- 

 tion known as the seamless method, which was distinctly Ameri- 

 can, and in opposition to the Siemens process. 



The rubber compound by this process was not necessarily cal- 

 endered or cut into strips, but was taken direct from the com- 

 pounding mills and fed into a screw machine which forced the 

 rubber in a compact and seamless mass around the conductor 

 as it emerged from a die in the end of the machine. This 

 process proved so satisfactory for high tension work that it 

 induced an American company to enter the field for the produc- 

 tion of submarine cables, which up to 1890 had been held almost 

 exclusively by English manufacturers. The first cable of this 

 character to be put in successful operation was laid during the 

 Spanish-American war by the cable ship Hooker, of the United 

 States army signal corps, and under the command of Colonel 

 James Allen. 



American Government Cables. 



When the American army established its base on the southern 

 coast of Cuba, after the blockade of Cervera's fleet in Santiago, 

 it was found necessary to place Cienfuegos in direct cable com- 

 munication with the United States. For this purpose a rubber 

 insulated conductor was designed, having a stranded copper core, 

 first insulated with a pure rubber jacket, over which was placed 

 a thicker layer of vulcanized rubber. This conductor was pro- 

 tected in the usual way by a steel armor, and after being success- 

 fully laid by the Hooker, placed the commander of the army 

 in Cuba in communication with Washington, and it was over 

 this cable that the news of the destruction of the Spanish fleet 

 was sent by Colonel Allen, within five minutes of the time of 

 its occurrence. 



Although this cable was of no great length, it proved to the 

 American government that india-rubber could stand more serv- 

 ice than gutta-percha, the material that before had been almost 

 universally used. The success of this cable naturally led to more 

 extended business, and with the acquisition of the Philippine 

 islands, india-rubber cables were laid connecting the entire group 

 with headquarters at Manila, and it has been stated that without 

 these cables as a means of communication for giving prompt 

 orders for the disposition of troops, the pacification of the islands 



