Modern Electrical Inventions. 53 



has been gradually reduced and is still getting lower in places 

 where it has been adopted on modern principles, the lecturer 

 proceeded to say that electric haulage was by no means confined 

 to tramways, as there was a large field for its employment in 

 the mining industry. He gave several examples of its successful 

 use in Scotch coal mines, and added that the system was being 

 taken up in several of the English collieries. Electric pumping 

 for mines and other purposes was next explained, and a very 

 complete triple pump in work was shown. The process of 

 drilling by electricity formed the subject of the next explana- 

 tion and demonstration. An electric drill an inch in diameter 

 being set to work, perforated a steel plate an inch thick in about 

 eighty seconds. The lecturer stated that these drills were 

 being now regularly used in all the Government dockyards, 

 and also by the French and Italian naval departments. All the 

 armour plates on H.M.S. Gibraltar, built by Napier Bros., were 

 drilled by one of these machines. They had been made to 

 drill holes three inches in diameter. Many of those present 

 who had visited the exhibitions in London and Glasgow must 

 have noticed the new process of welding. The system mostly 

 known was the Thomson, where an alternating current of two 

 hundred or three hundred volts is transformed down to a 

 pressure of one or two volts, and capable of giving out currents 

 often exceeding 100,000 amperes. The work capable of being 

 done by this system was, however, limited in extent, as it 

 required 50,000 amperes to weld a steel bar 1*5 in. diameter, 

 and for a bar of copper o'5 in. in diameter 25,000 amperes 

 would be wanted. The weld was made by clamping the bars 

 to be joined in place, and then bringing them together, when 

 they at once commenced to glow at the points of contact, and 

 the heat increased until the metal fused, when the clamps were 

 made to approach each other by means of a screw until the 

 pressure caused the weld to swell to a diameter larger than the 

 surrounding parts, when the article was removed and dressed 

 by the hammer on an anvil. The Bernardos system was far 

 more capable of general application— in fact could be used in 



