Page:Physical Geography of the Sea and its Meteorology.djvu/455

Rh observations of some of the vessels a cyclone may be made out. But if we take the observations of all of them, and discuss them upon the supposition that the whole storm was a cyclone, it will puzzle any one to make anything of them. Admiral Fitzroy, in the Meteorological Papers of the Board of Trade, published diagrams of the winds as observed during that storm on -board of various vessels in various parts of that sea. I have not been able to reconcile them with the cyclone theory. Espy maintains that they confirm his theory; and his (§ 787) is anti-cyclonic.

804. Cyclones of the North Atlantic.—The cyclones of the North Atlantic take their rise generally (§ 785) somewhere between the parallels of 10° and 20° north. They take a westerly course until they fall in with the Gulf Stream, when they turn about and run along upon it until their force is expended. The atmosphere over the Gulf Stream is generally well charged with moisture, and in this fact perhaps will be found the reason why (§ 176) the path of the storm is laid along the Gulf Stream.

805. The hurricane season.—The following table is from Birt's Handbook of Storms:

Average. Number of Cyclones or Hurricanes which have occurred in different Months of the Year, and in various Regions.

803. Cyclones in the Mississippi Valley.—The vortex of a cyclone is often and aptly compared to a meteor. I have often observed the paths of such through the forests of the Mississippi Valley, and the path of one of these "whirlwinds" as they are there called has in no instance that has fallen under my observation been more than a few hundred yards broad. There the track of these tornadoes is called a "wind-road," because they make an avenue through the wood straight along, and as clear of trees as if the old denizens of the forest had been felled with an axe. I have seen trees three or four feet in diameter torn up by the roots, and the top, with its limbs, lying; next the hole whence