John Munro

“ In 1835, at the Dublin meeting of the British Association, Wheatstone showed that when metals were volatilised in the electric spark, their light, examined through a prism, revealed certain rays which were characteristic of them. Thus the kind of metals which formed the sparking points could be determined by analysing the light of the spark. ”

“ This was the first apparatus which printed a telegram in type. It was worked by two circuits, and as the type revolved a hammer, actuated by the current, pressed the required letter on the paper. In 1840 Wheatstone also brought out his magneto-electrical machine for generating continuous currents, and his chronoscope, for measuring minute intervals of time, which was used in determining the speed of a bullet or the passage of a star. In this apparatus an electric current actuated an electro-magnet, which noted the instant of an occurrence by means of a pencil on a moving paper. ”

“ The same year he was awarded the Royal Medal of the Royal Society for his explanation of binocular vision, a research which led him to construct the stereoscope. He showed that our impression of solidity is gained by the combination in the mind of two separate pictures of an object taken by both of our eyes from different points of view. Thus, in the stereoscope, an arrangement of lenses and mirrors, two photographs of the same object taken from different points are so combined as to make the object stand out with a solid aspect. ”

“ They concluded with the words: 'It is to the united labours of two gentlemen so well qualified for mutual assistance that we must attribute the rapid progress which this important invention has made during five years since they have been associated.' The decision, however vague, pronounces the needle telegraph a joint production. If it was mainly invented by Wheatstone, it was chiefly introduced by Cooke. Their respective shares in the undertaking might be compared to that of an author and his publisher, but for the fact that Cooke himself had a share in the actual work of invention. ”

“ An experimental line, with a sixth return wire, was run between the Euston terminus and Camden Town station of the London and North Western Railway on July 25, 1837. The actual distance was only one and a half mile, but spare wire had been inserted in the circuit to increase its length. It was late in the evening before the trial took place. Mr. Cooke was in charge at Camden Town, while Mr. Robert Stephenson and other gentlemen looked on; and Wheatstone sat at his instrument in a dingy little room, lit by a tallow candle, near the booking-office at Euston. ”

“ Cooke, on the other hand, declared that his sole object was to make a fortune from the scheme. In May they agreed to join their forces, Wheatstone contributing the scientific, and Cooke the administrative talent. The deed of partnership was dated November 19, 1837. A joint patent was taken out for their inventions, including the five-needle telegraph of Wheatstone, and an alarm worked by a relay, in which the current, by dipping a needle into mercury, completed a local circuit, and released the detent of a clockwork. ”

“ Notwithstanding its success, the public did not readily patronise the new invention until its utility was noised abroad by the clever capture of the murderer Tawell. Between six and seven o'clock one morning a woman named Sarah Hart was found dead in her home at Salt Hill, and a man had been observed to leave her house some time before. ”