120 



THE INDIA RUBBER WORLD 



[January i, 1910. 



would have been impossible. In all, over 2,000 miles of rubber 

 conductors -were used in the cables of the Philippines system 

 and their perfect service under the most trying conditions proved 

 their great advantage for tropical regions, where the excessive 

 heat would in many cases ruin cables insulated with gutta-percha. 



Another point that was proved to the advantage of india-rubber 

 was the possibility of shipping the cables overland to San Fran- 

 cisco before they were placed on the cable ship, thus saving 

 ninety days in transportation. If gutta-percha cables had been 

 employed it would have been necessary to have sent them in 

 tanks of water to prevent the softening of the insulation, while 

 rubber which had been vulcanized at a temperature of over 

 200 degs. Fahr. was of course not affected by any unusual amount 

 of heat. 



Rubber Cables in Snow and Ice. 



No history of rubber insulation is complete without a note on 

 the important part it has played in the commercial conquest of 

 Alaska. When gold was discovered in the Klondike, electric 

 light and telegraph instruments had never been seen in that 

 region. With the inrush of the miner the American government 

 increased its military force to patrol the country and established 

 stations in the gold region farther and farther back from the 

 seacoast as successful explorations were made. These military 

 posts were of necessity connected by telegraph. 



It was found impossible to cut poles in that treeless waste, 

 and the question of transporting them over hundreds of miles 

 of rough country was impossible. To meet this emergency a 

 rubber insulated land cable was designed that could be laid over 

 the snow and ice and by this method keep up communication 

 with the outlying territory. This w^ire was placed on reels 

 strapped to dog sledges and played out in the most direct line 

 possible. In many places it soon became buried in snow and ice, 

 but was so designed that changes in temperature in no way 

 affected it. 



The rapidly increasing commercial importance of Alaska, due 

 not alone to the gold output, but to the immense fisheries and 

 fur interests, demanded still better means of communication. 

 During three months of the year it is impossible for ships to 

 arrive or depart from the icebound Alaska ports. This led to 

 careful investigation and the only solution of the difficulty was 

 a submarine cable connected with home. Very serious con- 

 sideration was given to the engineering problems involved. The 

 conditions were entirely new, as the shore end would be im- 

 bedded for a portion of each year in solid ice, and conditions 

 had to be met with that were entirely new in cable construction. 



Tests on india-rubber and gutta-percha were made under con- 

 ditions as near as could be artificially produced in a laboratory 

 comparing with the Alaska climate. The result proved a marked 

 advantage in favor of rubber, and bids were advertised for by 

 the United States army signal corps, for a deep sea submarine 

 cable approximately 2,000 miles long, connecting Seattle, in the 

 state of Washington, with Alaskan ports. 



As a result of these tests the Congress provided for a system 

 of telegraph lines and cables that should connect by an all- 

 American route, putting military stations in Alaska in telegraphic 

 connection with the army headquarters of the department of the 

 Columbia. At that time the chief signal officer of the army said 

 that the undertaking was unique in the annals of telegraphic 

 engineering, when one considered the extent of the territory, its 

 remoteness, the winter inaccessibility of the region, the severity 

 of the climate, the uninhabited and tractless districts, or the 

 adverse physical conditions. 



He stated that if this systemt were completed on a straight 

 line covering a map of the United States it would reach almost 

 across the continent, while the cables used would reach from 

 Newfoundland to Ireland. This plan comprised rubber insulated 

 wires for sttbmarine, land and other cables, all worked as one 

 component system. The entire construction consisted of 3,625 



miles of conductors. There are now installed and working cables 

 in Alaska connecting Skagway, Juneau, Sitka, Valdez, and Fort 

 Liscum with Seattle, in the state of Washington. 



A recent report from the war department states that although 

 it was a radical departure to use rubber insulated cables, and 

 that the Alaska line had been laid in depths up to 1.700 fathoms, 

 the cable had a greater comparative transmitting speed by 25 

 per cent, than that of the gutta-percha insulated Atlantic cables. 

 Insulation Machinery. 



The great increase in the use of rubber for insulating purposes 

 naturally demanded new types of machinery. The design and 

 manufacture of this new apparatus naturally fell to the com- 

 panies already making machinery for the rubber goods manu- 

 facture. When it is known that one insulating company has 

 fifty mills running almost continuously it will be seen that this 

 large amount of rubber compound must have an equal amount 

 of other machinery to apply it to insulating wire. 



At first a great many of the machines used for stranding the 

 rubber conductor, taping and braiding the rubber insulation, and 

 armoring the finished cable, were imported from England and 

 Germany. With the growth of the industry in America and the 

 high duty on machinery, the machine manufacturers at home 

 were led to turn out a line of work designed especially to meet 

 American requirements. The last twenty years have seen a tre- 

 mendous growth in this field, and with the present insulated 

 companies almost continuously increasing their plants and new 

 wire manufacturers coming in the field, a very lucrative business 

 has been established for this purpose. 



The rubber insulation manufacturer occupies a very peculiar 

 position in the commercial world. He must not only be an elec- 

 trical engineer, but a chemist as well. The manufacturer is 

 called on to meet the requirements for all classes of work from 

 the small telephone wire to the high tension underground cable. 

 The vast difference in voltage and conditions under which these 

 materials are used make it necessary to supply various grades 

 and thicknesses of rubber compounds. 



Reclaimed Rubber. 



While the government specifications call for 40 per cent, of 

 pure Para rubber combined only with dry mineral matter, the 

 grades of wire used for commercial work under less trying con- 

 ditions can safely be compounded with a less amount of pure 

 rubber and reclaimed stock. Although many engineering speci- 

 fications strictly prohibit the use of reclaimed rubber, careful 

 experiments have proven that it is an acquisition rather than a 

 detriment to an insulating compound, if properly used. It will 

 be readily seen that chemically reclaimed rubbers are not suitable 

 for insulating purposes, as the residue left is liable either to 

 attack the metal conductor or the textile fabric with which the 

 insulation is protected on the outside. High grade mechanically 

 reclaimed rubbers which are made from special stock in which 

 oil is not used to sheet them, can be highly recommended for 

 commercial insulating work, as such material makes a firmer 

 compound than one having a large percentage of chalk or other 

 fillers as ingredients, the reclaimed rubber naturally making a 

 compound less porous than with any of the hydroscopic materials. 

 Hard Rubber in Electricity. 



The use of hard rubber has also played a very important part 

 in the commercial introduction of electricity. In many places for 

 dynamo and motor construction, as well as in high grade instru- 

 ments, hard rubber has proved to be the only insulator that will 

 withstand the high voltages and prevent leakage. In the last 

 twenty years the output of hard rubber has steadily increased 

 until today the total amount produced is ten times greater than 

 it was in 1889. 



While substitutes for rubber insulations have been highly ad- 

 vertised and in many cases put in actual commercial service, 

 nothing has been found that will successfully take the place of 

 Para rubber for submarine cable work or high tension insulated 



