MATHEMATICAL AND PHYSICAL SCIENCE. 



[Diss. VI. 



for general adoption in a convenient form, is a matter 

 which we need not here decide. The three indepen- 

 dent inventors (I name them alphabetically) are Mr 

 Morse of the United States, M. Steinheil of Munich, 

 and Mr Wheatstone of London. The telegraph of 

 the two last resembles in principle Oersted's and 

 Gauss's ; that of the first is entirely original, and con- 

 sists in making a ribbon of paper move by clockwork, 

 whilst interrupted marks are impressed upon it by 

 a pen or stamp of some kind brought in contact with 

 the ribbon by the attraction of a temporary magnet, 

 which is excited by the circulation of the telegraphic 

 current of electricity. In the telegraphs of MM. 

 Wheatstone and Steinheil the needle moves only to 

 the right or left ; and by the combination of a certain 

 number of right and left motions, either with one or 

 with two independent needles acted on at once by 

 distinct currents, the alphabet is easily, though some- 

 what tediously constructed. Such, however, is the 

 dexterity which practice gives, that forty or even 

 more of such complex signals are transmitted and 

 registered per minute. 1 



(858.) It has already been said that we claim the exclu- 

 sive invention of the electric telegraph for no one in- 

 dividual. But of the several inventors none pro- 

 bably has shown such perseverance and skill in over- 

 coming difficulties as Mr Wheatstone. 2 His telegraph 

 accordingly was in general use in England before M. 

 Steinheil was able to obtain a similar success in 

 Germany. The telegraphs of Mr Morse are naturally 

 preferred in America, and they have this inestimable 

 advantage, that they preserve a permanent record of 

 the despatches which they convey. 



(859.) There is one circumstance connected with the elec- 

 The earth- ^ r j c telegraph deserving of particular notice I mean 

 the apparently infinite conducting power of the earth 

 when made to act as the vehicle of the return current. 

 Setting all theory aside, it is an unquestionable fact, 

 that if a telegraphic communication be made, sup- 

 pose from London to Brighton, by means of a wire 

 going thither, passing through a galvanometer, and 

 then returning, the force of the current shown by 

 the galvanometer at Brighton will be almost ex- 

 actly doubled, if, instead of the return wire, we 

 establish a good communication between the end of 

 the conducting wire and the mass of the earth at 

 Brighton. The whole resistance of the return wire 

 is at once dispensed with ! This fact was more than 

 suspected by the ingenious M. Steinheil in 1838; 

 but, from some cause or other, it obtained little 

 publicity ; nor does the author appear to have ex- 

 erted himself to remove the reasonable prejudices 



with which so singular a paradox was naturally re- 

 ceived. A most ingenious artist, Mr Bain, estab- 

 lished for himself the principle, and proclaimed its 

 application somewhat later; and in 1843, perhaps 

 the first entirely convincing experiments were made 

 by M. Matteucci at Pisa. From this time the double 

 wire required to move the needle telegraph was 

 reduced to a single one. The explanation of this 

 curious fact appears to be, not that the electricity 

 is conducted back by the earth to its origin at the 

 battery, but that the molecular disturbance po- 

 larly communicated along the conducting wire to its 

 farther end being effectually relieved by perfect com- 

 munication with a vast reservoir of neutral electri- 

 city like the earth, conduction proceeds in an unin- 

 terrupted manner, and to an unlimited extent. 



Of submarine telegraphs, it is sufficient to state (860.) 

 that the isolation is obtained by inserting the con- Submarine 

 ducting wires in a mass of gutta percha, and that tele S ra P h - 

 the first on a considerable scale was sunk between 

 Dover and Cape Gris Nez, on the French coast, in 

 August 1851. 



The applications of electricity to the measurement (861.) 

 of time are so numerous, that I can only refer ge- 

 nerally to the principal contrivances. 



1. The simple electric clock of Mr Bain derives its (862.) 

 maintaining power from two large plates of copper ^ 

 and zinc (or more simply zinc and charcoal) sunk in 



the earth, which affords for a very long time a con- 

 tinuous supply of voltaic electricity. The current is 

 conveyed into the bob of the pendulum, where it 

 traverses a long coil of wire ; and as the pendulum 

 oscillates, the current (by a simple shifting contriv- 

 ance) is reversed at each vibration. A stationary 

 bar-magnet is placed so that when the pendulum 

 moves, the voltaic coil of the bob embraces the mag- 

 net, and the direction of the current is such as by 

 the electro-magnetic reaction to strengthen and main- 

 tain the vibratory movement, which is by this means 

 perpetuated. 



2. Sympathetic clocks. By means similar to those (863.) 

 just explained, one standard clock anyhow regulated Sympathe- 

 may, by means of magneto-electric currents, convey tic clock 

 absolutely isochronous movements to any number of 

 affiliated clocks at any distance. Probably the first 

 application of the kind was made by M. Steinheil. 



3. American electric-registration clocks. Mr (864.) 

 Locke proposed to register the instant of an event American 

 occurring in the following way : A ribbon of rg 60 ;^". 

 paper being put in uniform motion, as in Morse's tion clocks. 

 telegraph, a dot is imprinted on it every second by 



1 Occasionally 18 or 20 words per minute have been telegraphed. 



2 I ought to mention that the practical introduction of the electric telegraph in England is in no small degree due to the 

 energy of Mr Fothergill Cooke, joint patentee with Mr Wheatstone for the invention. The question of the respective shares of 

 these gentlemen in the merit of telegraphic communication was submitted, in 1841, to the arbitration of Sir Marc Brunei and 

 the late Mr Daniell, the result of which appears to leave the preponderance of merit in some respects ambiguous ; neverthe- 

 less, in a history of Science, Mr Wheatstone is clearly entitled to the pre-eminent place. Several pamphlets have also been sub- 

 sequently published by the parties. It is significant that Mr Cooke admits having borrowed his idea from becoming acquainted, 

 at Heidelberg, in March 1836, with Gauss's experiments. 



