Messrs. Heaviside and Nixon, in their experiments at Newcastle-on-Tyne, have ascertained that the most effective wire was No. 4 of the English gauge. They employed wooden disks ⅛ inch in thickness, and these may be placed in any part of the length of the wire. When the wire was well stretched and motionless, it was possible to hear what was said at a distance of 230 yards, and it seems that Mr. Huntley, by using very thin iron diaphragms, and by insulating the line wire on glass supports, was able to transmit speech for 2,450 feet, in spite of the zigzags made by the line on its supports. _Mr. Graham Bell’s Electric Telephone._--Telephonic instruments were at this stage when Bell’s telephone was shown at the Philadelphia Exhibition of 1876. Sir William Thompson did not hesitate to call it ‘the wonder of wonders,’ and it instantly attracted universal attention, although there was at first much incredulity as to its genuineness. This telephone, in fact, reproduced articulate words, a result which surpassed all the conceptions of physicists. In this case it was no longer a conception, to be treated as visionary until there was proof to the contrary: the instrument spoke, and even spoke so loudly that it was not necessary to apply the ear. Sir William Thompson spoke to this effect on the subject at the meeting of the British Association at Glasgow in September 1876:-- ‘In the department of telegraphs in the United States I saw and heard Mr. Elisha Gray’s electric telephone, of wonderful construction, which can repeat four despatches at the same time in the Morse code, and, with some improvements in detail, this instrument is evidently capable of a fourfold delivery. In the Canadian department I heard “To be or not to be? There’s the rub,” uttered through a telegraphic wire, and its pronunciation by electricity only made the rallying tone of the monosyllables more emphatic. The wire also repeated some extracts from New York papers. With my own ears I heard all this, distinctly articulated through the slender circular disk formed by the armature of an electro-magnet. It was my fellow-juryman, Professor Watson, who, at the other extremity of the line, uttered these words in a loud and distinct voice, while applying his mouth to a tightly stretched membrane provided with a small piece of soft iron, which executed movements corresponding to the sound vibrations of the air close to an electro-magnet introduced into the circuit. This discovery, the wonder of wonders in electric telegraphy, is due to a young fellow-countryman of our own, Mr. Graham Bell, a native of Edinburgh and now naturalised in New York.