A correspondent of the Evening Post, this city, writing on this subject, endeavors to prove that the entire volume of the ocean must be about a temperature of 39, and Lieut. Berryman's deep sea soundings (which have been noticed in our columns) by which a temperature of 20 below the freezing point was found, arc attributed to a defective instrument. We have received a letter which will appear in our next number, in wbieh facts will be given in proof of the correctness of Lieut. Berryman's soundings.