ABSTRACT
Cook’s voyages, and that of HMS Beagle and other survey ships, were primarily concerned with charting coastlines; but by the second half of the nineteenth century there was increasing interest in the deep seas, and the voyage of HMS Challenger in 1873-76 marks the beginning of oceanography. This ship carried a laboratory, and was specially adapted for a scientific voyage. Earlier scientists had often been exasperated at the lack of room on board ship, and at the way their time ashore was restricted because the boats were often needed for survey work, and the naturalists could not be allowed to wander away among suspicious or hostile natives. It is striking how much work was done by those such as Sabine, Darwin, Huxley and Joseph Hooker who made the best of it all. J. F. W. Herschel (ed .) (1974) The Admiralty Manual of Scientific Enquiry (1851
Wave motions we are familiar with from the sea. When we watch the rollers coming in from the Atlantic ocean, the movement of the molecules of water has only been up and down. The wave may travel from Cape Cod to Land’s End, but the water does not. Water-waves are called transverse, because the motion is at right-angles to the line in which the wave is going. In the sea, the particles can only move up and down; but one can imagine three-dimensional waves in which the vibrations were in all possible planes at right-angles to the direction of propagation. Another sort of wave is the longitudinal; here the particles vibrate in the line of propagation. Sound waves are supposed to be of this kind. The molecules of air move back and forth, none coming all the way from the source to our ear.
