294 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



and, even from the depths to which no ray of light is callable of 

 penetrating, the sounding-lead brings up news at least of living 

 infusoria." — Schleiden's Lectures, p. 403 — 406. 



561. Until the commencement of the plan of deep-sea soundings, 

 i^^° hTdc- Tif o7°" ^ ^^ ^^-^^y \\^YQ been conducted m the American and 

 " blue water." English navics, the bottom of what the sailors call 

 " blue water " was as unknown to us as is the interior of any of the 

 planets of our system. Boss and Dupetit Thouars, w4th other officers 

 of the Enghsh, French, and Dutch navies, had attempted to fathom 

 the deep sea, some mth silk threads, some mth spun-yarn (coarse 

 hemp threads tmsted together), and some with the common lead 

 and line of na\dgation. All of these attempts were made upon 

 the supposition that when the lead reached the bottom, either a 

 shock would be felt, or the hne, becoming slack, would cease to 

 run out. ♦ 



562. The series of systematic experiments recently made upon 

 Early attempts at this subjcct sliow that there is no reliance to be 

 Snwortby of ?e°it pl^ccd ou such a suppositiou, foT the shock caused 

 '"ice. by striking bottom cannot be communicated through 

 very great depths. Fuirthermore, the hghts of experience show 

 that, as a general rule, the under currents of the deep sea have 

 force enough to take the line out long after the plummet has ceased 

 to do so. Consequently, there is but httle reliance to be placed 

 upon deep-sea soundings of former methods, vdien the depths reported 

 exceeded eight or ten thousand feet. 



563. Attempts to fathom the ocean, both by sound and pres- 

 various methods surc, had bccn made, but out in "blue water" every 

 tried or proposed, ^^g^j ^j^^ Q^]y g^ failure repeated. The most ingenious 

 and beautiful contrivances for deep-sea soundings were resorted to. 

 By exploding petards, or ringing bells in the deep sea, when the 

 Vvinds V\'ere hushed and all was still, the echo or reverberation from 

 the bottom might, it was held, be heard, and the depth determined 

 from the rate at which sound travels through water. But, though 

 the concussion took place many feet below the sm^face, echo was 

 silent, and no answer was received from the bottom. Ericsson 

 and others constructed deep-sea leads having a column of air in 

 them, which, by compression, would show the aqueous j)ressm'e to 

 which they might be subjected. This was found to answer well 

 for ordmary purposes, but in the depths of the sea, where the pres- 

 sure would be equal to several hundred atmospheres, the trial was 

 more than this instrument could stand. Mr. Baur, an ingenious 



