HARDWICKE'S SCIENCE-GOSSIP. 



15 



The Western Union Telegraph Company (the 

 lessees of the lines of the American Telegraph and 

 Cable Comijany) has two cables from Sennen Cove, 

 Land's End, to Canso, Nova Scotia (4). The cable 

 of 1S81 is 2531, and that of 1882 is 2576 miles in 

 Jength. Two cables were laid in November 1S89 

 between Canso and New York (14). 



The Compagnie Fi-ancaise du Telegraphe de Paris 

 a New York, has a cable from Brest to St. Pierre 

 ^Miquelon, of 2242 miles in length (5), from thence a 

 cable is laid to Louisbourg, Cape Breton (12), and 

 another to Cape Cod (13). It has also a cable from 

 Brest to Porcella Cove, Cornwall (11). 



Those ten cables owned by the six companies 

 named, of the total mileage of 22,959, i^ot counting 

 connections, represent the entire direct communica- 

 tion between the continents of Europe and North 

 America. 



A new company, not included in the preceding 

 statistics, proposes to lay a cable from Westport, 

 Ireland, to some point in the Straits of Belle Isle on 

 the Labrador coast (Map A 32, Map B 20). 



The station of the Eastern Telegraph Company is 

 at Porthcurno Cove, Penzance, from whence it has 

 two cables to Lisbon, one laid in iSSo, 850 miles 

 dong, the other laid in 1887, 892 miles long (12), and 

 one cable to Vigo, Spain, laid in 1873, 622 miles 

 long (13). From Lisbon the cable is continued to 

 ^Gibraltar and the East, whither we need not follow 

 it, our intention being to confine ourselves entirely to 

 a brief account of those cables communicating 

 'directly with Europe and America. As already 

 stated, this company has altogether seventy cables of 

 a total length of nearly twenty-two thousand miles. 



The Direct Spanish Telegraph Company has a 

 cable, laid in 1884. from Kennach Cove, Cornwall, 

 to Bilbao, Spain, 486 miles in length (14). 



Coming now to shorter cables connecting Britain 

 with the Continent, we have those of the Great 

 Northern Telegraph Company, namely, Peterhead to 

 Ekersund, Norway, 267 miles (15), Newbiggin, 

 near Newcastle, to Arendal, Norway, 424 miles, and 

 thence to Marstrand, Sweden, 98 miles. 



Two cables from the same place in England to 

 Denmark (Hirstals and Sondervig) of 420 and 337 

 miles respectively (17 and 18). 



The Great Northern Company has altogether 

 twenty-two cables, of a total length of 6110 miles. 

 The line from Newcastle is worked direct to Nylstud, 

 in Russia — a distance of S90 miles — by means of a 

 *' Relay" or "Repeater," at Gothenburg. The 

 Relay is the apparatus at which the Newcastle 

 •current terminates, but in ending there it itself starts 

 a fresh current on to Russia. 



The other Continental connections belong to the 

 Governmment, and are as follows : two cables to 

 Germany, Lowestoft to Norderney, 232 miles, and to 

 Emden, 226 miles (19 and 20). 



Two cables to Holland : Lowestoft to Zandvoort, 



laid in 1858 (21), and from Benacre, Kessingland, to 

 Zandvoort (22). 



Two cables to Belgium : Ramsgate to Ostend (23), 

 and Dover to Furness (24). 



Four cables to France : Dover to Calais, laid in 

 1S51 (25), and to Boulogne (26), laid in 1859; 

 Beachy Head to Dieppe (27), and to Havre (28). 



Thei^e is a cable from the Dorset coast to Alderney 

 and Guernsey, and from the Devon coast to 

 Guernsey, Jersey, and Coutances, France (29 and 



30)- 



A word now as to the instruments used for the 

 transmission of messages. Those for cables are of 

 two kinds, the Mirror Galvanometer, and the Syphon 

 Recorder, both the product of Sir Wm. Thompson's 

 great inventive genius. 



When the Calais-Dover and other short cables 

 were first worked, it was found that the ordinary 

 needle instrument in use on land-lines was not 

 sufticiently sensitive to be affected trustworthily by 

 the ordinary current it was possible to send tlirough 

 a cable. Either the current must be increased in 

 strength, or the instrument used must be more 

 sensitive. The latter alternative was chosen, and the 

 Mirror-Galvanometer was the result. The principle 

 on which this instrument works may be briefly 

 described thus : the transmitted current of electricity 

 causes the deflection of a small magnet, to which is 

 attached a mirror about the three-eighths of an inch 

 in diameter, a beam of light is reflected from a 

 properly-arranged lamp, by the mirror, on to a paper 

 scale. The dots and dashes of the Morse code are 

 indicated by the motions of the spot of light to 

 the right and left respectively , of the centre of the 

 scale. 



Tlie Mirror-Galvanometer is now almost entirely 

 superseded by the Syphon-Recorder. This is a some- 

 what complicated apparatus, with the details of which 

 we need not trouble our readers. Suffice it for us to 

 explain that a suspended coil is made to communicate 

 its motions, by means of fine silk fibres, to a very fine 

 glass syphon, one end of which dips into an insulated 

 metallic vessel containing ink, while the other extremity 

 rests, when no current is passing, just over the centre 

 of a paper ribbon. When the instrument is in use 

 the ink is driven out of the syphon in small drops l)y 

 means of an electrical arrangement, and the ribbon 

 underneath is at the same time caused to pass under- 

 neath its point by means of clockwork. If a current 

 be now sent through the line, the syplion will move 

 above or below the central line thus giving a 

 permanent record of the message, which the mirror- 

 instrument does not. The waves written by the 

 syphon above the central line corresponding to the 

 dots of the Morse Code, and the waves underneath 

 corresponding to the dashes. 



The cost of the transmission of a cablegram varies 

 from one shilling per word, the rate to New York and 

 east of the Mississippi, to ten shillings and sevenpence 



