In early March of 1873, Professor Wyvillle-Thomson, at the request of Captian Nares, presented a lecture for the entire Challenger company. Serving to break the monotony of the long Atlantic transit, and to engage the crew and foster an interest in the expedition's scientific endeavors, the entire lecture was transcribed, it appears nearly verbatim, by Joseph Matkin, who included the entire text in his correspondence with the people at home.
"Substance of Professor Wyville Thompson's Lecture, to the ship's company of H.M. Ship "Challenger," on the Geography of the sea, & the object of the "Challenger" Expedition. With remarks on the progress hitherto made:
"I have been asked by the Captain to try & explain to you, as well as I am able, what is the object of our expedition & what we are doing from day to day. I need not remark that it gives me pleasure so do to, for we are to be common shipmates for the next few years, & doubtless, each one has some interest in the work, & the results, if successful, will be creditable to us all.
"In the first place I must tell you that the bottom of the sea occupies an area of three quarters of the globe and this immense portion has hitherto been as a sealed book to the human race. We have a comparatively accurate notion of the Land; we know the geology and the Natural History of most of the Countries of the earth, even Africa and Australia, are becoming annually more known to us, & the indomitable energy of man is slowly but surely bringing each country into what I may call the regular routine, and causing it to contribute somewhat to the comfort & happiness of the rest; inasmuch as their productions (whether natural or artificial) whether as necessaries, or more generally as luxuries are spread in this manner over the world, and in this way conduces to the general happiness of mankind.
"One reason why our ancestors did nothing toward lifting the veil from the sea bottom was because it was thought that no object could be gained by so doing, and the difficulties in the way were deemed insurmountable. For it was thought, and with reason, that nothing living could exist at a grater depth than about 400 fathoms. Now you all know that where an empty bucket is put over the Ship's side and allowed to sink down a little distance what difficulty there is in hauling it up, and what a resistance is offered by the weight of water on the top of it. That resistance increases the lower we go; so that if a man was placed at the bottom where we were to day sounding, 2,800 fathoms, he would have a weight pressing on him equal to the weight of the Challenger.
To explain this, I must tell you that a man's body presents a surface of 375 square inches, and that at 2,800 fathoms the weight of a column of water would be over 3 tons to the square inch. If the island of Tenerife was sunk in the place we were today, the Peak would scarcely reach the surface of the water. These are among the principal reasons for the former statement (which we, as well as others , have proved to be false) "that no animal life was to be found lower than about 400 fathoms." It is now less than 20 years ago that scientific men began to talk of a scheme of Ocean telegraphs, whereby the continents of America and Europe might be placed in almost instantaneous communication. How this scheme has succeeded we all know, but in the outset it was resolved by all practical men that some knowlege of the nature of the sea bottom was imperative, to enable the cables to be laid with any degree of accuracy and safety. Soundings, therefore, were at once taken across that portion of the Atlantic where the cables were to be laid. The Americans, as well as other nations, commenced a series of Atlantic soundings, which have been continued more or less ever since.