Page:Physical Geography of the Sea and its Meteorology.djvu/47

Rh independent of these facts and views, there is another reason why iron wrappings and two metals should not he used, at least for deep-sea cables. Our researches at sea have shown that there is no running 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 disturb it more. Wherefore it has been held, that the iron wrapping for deep-sea lines of telegraph, instead of being advantageous in any aspect, are not only a hindrance, but an incumbrance also and a waste: the weight of the cord may be adjusted to sinking by the size of the conducting wire within as well as by the character of the non-metallic wrapping without.

66. Rogers's cable "jacket."—Whether the insulating material be gutta-percha, india-rubber, or other matter, it requires to be protected from 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 running water. Thus one of the obstacles which have been interfering with the progress of submarine telegraphy is removed out of the way.

67. Deep-sea temperatures a desideratum.—But notwithstanding all that has been done with the sea and in the sea for the electro-magnetic telegraph, and for human progress, there still remain many agenda. There is both room and need for further research, more exploration, and many experiments. As bearing upon the best insulating 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 phenomena of the sea, are there none who will make deep-sea temperatures a speciality? They would no doubt prove as instructive and as useful too as deep-sea soundings have been and are.