190 Britain's Heritage of Science 



The next attempt, made after an interval of eight years, 

 was again unsuccessful; but in 1866 the Great Eastern 

 laid its cable without mishap, and was even able to pick up 

 the lost end of the one that had broken in the previous year. 

 Since then submarine cables, mostly manufactured in Eng- 

 land, have rapidly increased, and their total length now at 

 work would, if joined end to end, be able to pass ten times 

 round the equator. 



The success of cables depends so much on the durability 

 of the insulating material that this seems to be the place 

 for attention to the services of Thomas Hancock (1786- 

 1865), the founder of the india-rubber trade in England. 

 His work is well described in the " Dictionary of National 

 Biography," from which the following account is with a 

 few omissions transcribed. Observing that two freshly 

 cut surfaces of india-rubber readily adhered by simple 

 pressure, Hancock was led to the invention of the " masti- 

 cator," as it was afterwards called, by the aid of which 

 pieces of india-rubber were worked up into a plastic and 

 homogeneous mass. With the invention of this process, 

 which was perfected about 1821, the india-rubber trade 

 commenced. Eventually, Hancock became a partner in 

 the firm of Charles Macintosh and Company, though he still 

 carried on his business in London. In 1842 specimens of 

 " cured " india-rubber, prepared in America by Charles 

 Goodyear according to a secret process, were exhibited in 

 this country. Hancock investigated the matter, and dis- 

 covered that when india-rubber was exposed to the action 

 of sulphur at a certain temperature a change took place; 

 he thus obtained " vulcanized " india-rubber. This was 

 patented in 1843. Although Hancock was not the inventor 

 of vulcanizing in the strictest sense of the word, he first 

 showed that sulphur alone is sufficient to effect the change, 

 whereas Goodyear employed other substances in addition. 

 Hancock also discovered that, if the vulcanizing process be 

 continued and a higher temperature employed, a horny 

 substance, now called vulcanite or ebonite, is produced. 



David Edward Hughes (1831-1900), whose name has 

 already been mentioned above, was born in London, but 

 his parents emigrated to the United States when he was 



