26 ANNUAL OF SCIENTIEIC DISCOVERY. 



only will this subdivision of the cable reduce mechanical risks in 

 sul)merging, but, what is of fur nioi-c importance, the retardation 

 offered to tlie passage of the current through the several short 

 sections is almost as nothing when compared with that of the un- 

 broken length of 2,000 miles. Speeil of transmission is obtained ; 

 and by that means a reduced tariff for i)uljlic transmissions over 

 the wire. Indeed, such will be tlie advantages gained in this 

 respect that the present rate by the Anglo-American line of 20s. 

 per word, will be charged on the new route at 2s. (5d., or even a 

 less sum. In examining more closely the nature of tliis intended 

 northern line, it will bv. found that the lengths of the several 

 sections of ealjle between England and America are as follows : 

 Scotland to the Faroe Isles, 250 miles; Faroe to Iceland, 210 

 miles ; Iceland to Greenland, 7.30 miles ; Greenland to Labrador, 

 5-40 miles; or, in rouml numbers about 1,780 miles. The several 

 lengths of cable will be connected together by special land lines 

 through the Faroes (27 miles), and in Iceland (280 mikis), and a 

 length of about GOO miles of land wire to be erected in Labrador, 

 will com])lete the circuit, with the existing American system, on 

 to New York. The average depth of the ocean between Scotland 

 and the Faroe Isles is only 150 lathoms, the greatest depth G83 

 fathoms. Between the Faroes and Iceland, 250 fathoms, with 

 about the same maximum depth. Between Iceland and Julian- 

 shaad, the intended landing-place of the cable in Greenland, the 

 greatest depth is 1,550 fathoms, and between Greenland and Lab- 

 rador rather over 2,000 fathoms. These lengtlis of cable and 

 depths of ocean are both not only navigable, but practicable ; and 

 no difficulties in the working exist that are not already known l)y 

 reference to the practical working of existing cables under the 

 conditions of similar lengths and depths. As regards the presence 

 of ice, it must be remembered that it is only at certain seasons of 

 the year that the southwest coast of Greenland is closed by the ice ; 

 at other times this ice breaks up, and the coast is accessible to the 

 Danish and otlier trading vessels frequenting the port and harbor 

 of -Julian^haad, the proposed station and landing-place of the 

 cables, and at such times the cables will I)e laid. Reference to 

 the depth of the soundings up the Julianshaad fjiord will at once 

 indicate the security of tlie shore ends of tlie cal:)les from inter- 

 fei'ence from ice Avhen submerged. The landing-places of the 

 cable in Iceland are likewise in no way liable to be disturbed by 

 ice of such a nature as to cause damage to the cable ; and on tlie 

 Labrador coast, the risk of injury to the cable cannot be consid- 

 ered greater than that to Avhich the Anglo-American shore ends 

 are exposed in the vicinity of Newfoundland Bank. — J. Holmes, 

 in Reports of British Association for 1866. 



TUNNEL UNDER LAKE MICHIGAN AT CHICAGO, ILL. 



The following account of one of the most remarkable and suc- 

 cessful feats of American engineering is compiled from various 

 sources, princiiially the llejiorts of the Board of Public Works, 

 Chicago, the "Scientific American," and the Boston " Coumion- 

 wealtii." This work is now virtually completed, and for boldness 



