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Colonel Lloyd, one of the special (commissioners of the Exhibition, exhibited a very remarkable instrument, called a typhoductor, or storm pointer—an instrument for obtaining by inspection the bearing and relative position of a revolving storm or hurricane. It is now a well ascertained fact, that great storms have a rotary motion, like a whirlwind. The theory commonly called the law of storms, as made known in several publications by persons ol eminence, has been established from thousands of well authenticated observations in different parts of the world, and extending over a period of several years. It proves that during a gale ot wind, particularly near to the tropics, the wind blows with the greatest fury round a common centre; at this centre there is little or no wind, even a perfect calm; but there is generally a terrific and confused sea. The most violent and dangerous parts of these revolving gales are near this central calm, the wind there blowing the most fiercely, acquiring, it is stated, a velocity of even a hundred miles an hour. These storms sweep both land and sea in certain parts of the globe; their track and direction are pretty well known, and they travel bodily from their place of origin to their destination at variable speeds—sometimes at not more than fouro-eijc milfispex hour; sometimes, but seldom, at that of 20 to 30 miles per hour, although the wind within their range is blowing round with the fury just mentioned. If a ship unhappily becomes entangled within the range of these terrible gales, she is in great peril. Many have foundered, and others have pursued their fearful course round and round until they have been reduced to helpless wrecks, dismasted and water-logged. In the northern hemisphere, these winds blow round the compass from east by north, to west, or the contrary way to the hands of a watch; whereas in a southern hemisphere it is just the reverse, blowing round as the hands of a watch would go. This principle must always be borne in mind as the very foundation ol all the information to be sought hereafter. On these most valuable data, instructions have been drawn up by Colonel Reid, and others, how to ascertain the relative position of a gale, so as to know whether it is approaching to or going from a ship, travelling by its side, or crossing its path. The object of Colonel Lloyd's ingenious instrument is, by graphic illustration, to show that when the wind blows from a particular point of the compass, you can only be in one relative position in regard to the centre of the whirl storm, so that either the storm is approaching the ship or the ship approaching the storm, and first, of course, encountering the outer edge. As a consequence of the law of rotation, the wind, supposing the whirl to be circular, must blow at a tangent or right angles to the point of the compass where the ship or observer may be, but under diametrically opposite conditions, as far as regards the two hemispheres. Thus in a northern hemisphere, if the wind blows east, the centre of the storm must be due south of the observer; blowing north, the vortex east; coming from the west, the centre of the gale is north; and, lastly, with the wind south, the gale is due west. Of course, in the intermediate points of the compass, the bearings are likewise different. In a southern latitude the whirl-storm blows round just the contrary way. With an east wind the storm centre bears north; with a north wind, west; with a west wind, south; and with a south wind, east. Bearing in mind these factsf and with sea-room, it is easy not only to avoid hurricanes, but to make them subservient, in many cases, to the ship's ultimate course.
