From Houghtalings Handbook ©1887
The sea cocupies three-fifths of the surface of the earth. AT the depth of about 3,500 feet waves are not felt. The temperature is the same, varying only a trifle from the ice of the pole to the burning of the sun of the equator. A mile down the water has a pressure of over a ton to a square inch. If a box six feet deep were filled with sea water and allowed to evaporate under the sun, there would be two inches of salt left on the bottom. The water is colder at the bottom than at the surface.