. Bulletin. Science. Figure 19.—VVheatstone and Cooke's local circuit (including relay and call alarm) for their 1837 telegraph. From G. B. Prescott, History, Theory, and Practice of the Electric Telegraph, Boston, i860, p. 414. proposal to connect all government buildings in Eng- land by a network of telegraph lines. The telegraph system between London and Slough was the first one in England to be opened to public service. The ef- fectiveness of communicating by telegraph was proved during the troubled times of 1848 and during the Crimean War. In the 1850's telegraph lines spread rapidly thro
. Bulletin. Science. Figure 19.—VVheatstone and Cooke's local circuit (including relay and call alarm) for their 1837 telegraph. From G. B. Prescott, History, Theory, and Practice of the Electric Telegraph, Boston, i860, p. 414. proposal to connect all government buildings in Eng- land by a network of telegraph lines. The telegraph system between London and Slough was the first one in England to be opened to public service. The ef- fectiveness of communicating by telegraph was proved during the troubled times of 1848 and during the Crimean War. In the 1850's telegraph lines spread rapidly throughout the continent and Great Britain, and by April 1855 London could communicate directly with Sebastopol. Wheatstone and Cooke also invented another kind of telegraph instrument, known as the dial telegraph. The first version of this system, worked out by Cooke in 1836, was based upon two synchronous m^e- chanical clocks, the one at the transmitting station indicating the letter as the one at the receiving station. The transmitting station closed the circuit and permitted the lettered dial on both clocks to turn until the letter desired was indicated at the transmit- ter; whereupon the circuit was opened and the clocks stopped. Since the clocks were synchronized, the receiving one would stop at the same letter as the transmitting one. The transmitting station would then perform the same operations for the next letter and so on. This synchronous system was difficult to reduce to practice, so Wheatstone and Cooke patented another version of a dial telegraph on January 21, 1840 (British patent 8345). Li this case the dial at the receiver was dri\-en b\" the transmitting dial instead of being controlled in its motion at the receiving station. Moving an indicator over the dial at the transmitting station sent a number of pulses down the line according to the number of letters passed over. These pulses released an escapement, allowing a weight-driven pointer to turn u
Size: 2205px × 1133px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorunitedstatesdepto, bookcentury1900, booksubjectscience
