20 PHYSICAL GEOGEAPKY OF THE SEA, AKD ITS METEOROLOGY. 



cable itself is a long and powerful Leyden jar, the iron ^Tapping 

 assists to make it so. This circumstance may also assist to excite 

 the two metals still more, and so hasten the destruction of the cable 

 as an electrical conductor. 



65. But independent of these facts and views, there is another 

 Two metals should I'^ason why iron wrappings and two metals should 

 not be used about not be usod, at Icast foT doep-sca cables. Our 



a submarine cable. , , ■, ■, , i . n 



researches at sea have sho^n that there is no run- 

 ning water at the bottom of the deep sea. Hence we infer that a 

 telegraphic cord once lodged on the bottom of the ocean, there, as 

 the tree that falls in the forest, it would lie ; for there is nothing 

 to distm'b it more. Wherefore it has been held,* that the iron 

 ^vrapping for deep-sea lines of telegraph, instead of being advan- 

 tageous in any aspect, are not only a hindrance, but an incum- 

 brance also and a waste : the weight of the cord may be adjusted to 

 sinking by the size of the conducting wire WTthin as well as by the 

 character of the non-metallic -swapprng without. 



6Q. Whether the insulating material be gutta percha, india- 

 Rogers's cable Tubber, OT othoT matter, it requires to be protected 

 "jacket." fj,Qj^ chafes and bruises while on board, and when it 



is being payed out. And it may be so protected by a covering, not of 

 wire, but of silk, hemp, flax, or cotton. An ingenious American! 

 has invented a "jacket," which will not only protect the cable 

 while on board, but afterwards also, and when it is at the bottom 

 even in shallow and rmming water. Thus one of the obstacles 

 vdiich have been interfering mth the progress of submarine tele- 

 graphy is removed out of the wa^^ 



67. But notwithstanding all that has been done with the sea 

 j).v.p.sea tempera- a^d iu the sca foT the elcctro-magnetic telegraph, 

 tur.^s a desideratum. ^^-^^_ f^^, human progrcss, there still remains many 

 agenda. There is both room and need for further research, more 

 exploration, and many experiments. As bearing upon the best in- 

 sulating material for submarine lines of telegraph, a good series of 

 deep-sea temperatures is much needed. Of all those who are now 

 engaged in observing and studying with us, and for us, the pheno- 



* Vide Letter to Secretary of the Navy, November 8, 1856. Maurys' 

 Sailing Directions, chapter Submarine Telegraphy ; ditto, Physical Geo- 

 graphy of the Sea, chapters XIII. and XXI., Harper Brothers, New York, 1859 ; 

 also Journal Royal Dublin Society, numbers XII. and XIII. Letter to 

 John Locke, on tlie Atlantic Telegraph causes of failure and probabilities of 

 ultimate success. Read January, 1859. 



t Henry J. Rogers of Baltimore, 



