The Deep-sea Sounding Apparatus of Lieutenant Brooke has already furnished some very remarkable results. Aided by it, Dr. Maury has constructed his fine orographic map of the basin of the Atlantic, which is probably as exact as the maps which represent Africa or Australia. Dr. Maury has also published many charts, giving the depths of the ocean, the substance of which is given in the accompanying map, which represents the configuration of the Atlantic up to the tenth degree of south latitude, not in figures, as in Dr. Maury's charts, but in tints; diagonal lines from right to left, representing the shores of both hemispheres, indicate a depth of less than a thousand fathoms; from left to right, indicate bottom at one thousand to two thousand; horizontal lines, two to three thousand fathoms; cross lines show an average depth of three to four thousand fathoms; finally, the perpendicular lines indicate a depth of four thousand fathoms and upwards. Solid black indicates continents and islands; waving lines, surrounding both continents at a short distance from the shore, indicate the sands which surround the coast line at a little distance from the shore. [Illustration: Fig. 2. Chart of the Atlantic Ocean.] * * * * * The question may be asked, what useful purpose is served by taking soundings at great depths? To this we may quote the answer of Franklin to a question of similar tendency, addressed to aeronauts--"What purpose is served by the birth of a child?" Every fact in physics is interesting in itself; it forms a rallying point, round which, sooner or later, others will meet, in order to establish some useful truth; and the importance of making and recording deep-sea soundings is established by the successful immersion of the transatlantic telegraph.