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THE POPULAR SCIENCE MONTHLY.

tion aloft sets in, and the precipitation only serves to add "fuel to the flames" of the cyclonic engine. This process widens in geographical area, and, after a few hours have elapsed, the storm may so develop as to cover a continent with its portentous canopy of cloud, while simultaneously strewing an ocean with wrecks, and throwing out, in the upper sky, more than a thousand miles in its front, the fine filaments of the premonitory cirrus and cirronus.

Fig. 1.

cirrus-cirronus clouds.

In close connection with the size and magnitude of cyclones must be considered the distance over which they pass from their initial point. Much has been said on this part of our subject, and not a few writers have accepted the doctrine of Admiral Fitzroy that they progress over but comparatively short distances. For such a view, however, it is impossible to find, either in the nature or physical office of the cyclone, any support whatever. The storm once engendered, no matter in what part of the world, may be stationary or progressive. There are well-authenticated instances of almost stationary cyclones and almost stationary typhoons, of which latter will be remembered the famous gale of the ship Charles Heddle—an Indiaman, carried round and round the storm-centre for five days—which progressed not more than ninety miles a day. Indeed, we may, as has been said, regard every wet-monsoon region as a stationary and semi-perennial cyclone.