Dark And Cold As Zero

Tne peculiar physical couditions of ie deep Reas may be briefly stated to be ïese: It is absolutely dark, sq f ar as ctual sunlight is concerned; tlie temerature is only a few degrees above 'reezing point, the pressure is enormous, ïere is little or no movement of the water, the bottoin is composed of a ini'orm, fine, soft mud, and there is no )lant life. All of these physical condiions one can appreciate, except the normous pressure. At a depth of 2, 500 athoms the pressure is, roughly epeakng, 2 tons per square inch - that is to say, the pressure per square inch upon the body of every animal that lives at the bottom of the Atlantic ocean is about 25 times greater than the pressure that will drive a railway train. Professor Moseley describes an interesting experiment in point made during the voyage of the Challenger, ilr. Bucliauiin henuetically sealed at botb ends a thick ghiss lulu' lull of air and several inehes in lengt h. He wrapped it in flaunel and placed it in a wide copper tube, one of those used to protect tho deep sea thermometers when sent down with the smmding apparatiis. This copptr tube was closed by a lid fitting loosely and with holes in the bottom of it, and the copper bottom of the tube similarly had holes bored through it. Tho water thus had free access to the interior of the tube when it was lowered into the sea, and the tube was necessarily constructed with that object in view, so hat in its orilinary use the ■water shoulcl ïeely reach the containecl thermometer. The copper case contaiuing the sealed ;lass tube was sent clown to a depth of 2,000 fathoms and clrawn up again. It vas then fonnd that the copper wall of iie case was bulged and bent iuward opposite the place where the glass tube ay, just as if it had been crumpled invard by being violently squeezed. The glass tube itself, within its flannel wrapper, was fouud when withdrawn reduced to a fine powder, like snow almost. What had happened was that the sealed glass tube, sinking to gradually iucreasing depths, had held out long igainst the pressure, but this at last ïad become too great for the glass to sustain, and the tube had suddenly given way. So violent had been the collapse hat the water had not had time to rush in at the perforations, but instead had crushed in the copper wall and brought equilibrium in that manner, and this process is exactly the reverse of an explosión and is termed by Sir Wyville