By a like reasoning, we can account for the cyclonic storms prevailing in the North Pacific Ocean. Nor do the tornadoes which rage in parts of the United States present any serious difficulty. The region along which these storms travel is the valley of the great Mississippi. This river at certain seasons is considerably warmer than the surrounding lands. From its surface, also, aqueous vapour is continually being raised. When the surrounding air is colder, this vapour is presently condensed, generating in the change a vast amount of heat. We have thus a channel of rarefied air over the Mississippi valley, and this channel becomes a storm-track, like the corresponding channels over the warm ocean-currents. The extreme violence of land-storms is probably due to the narrowness of the track within which they are compelled to travel. For it has been noticed that the fury of a sea-cyclone increases as the range of the ‘whirl’ diminishes, and _vice versâ_. There seems, however, no special reason why cyclones should follow the storm-⊂ in one direction rather than in the other. We must, to understand this, recall the fact that under the torrid zones the conditions necessary for the generation of storms prevail far more intensely than in temperate regions. Thus the probability is far greater that cyclones should be generated at the tropical than at the temperate end of the storm-⊂. Still, it is worthy of notice, that in the land-locked North Pacific Ocean, true typhoons _have_ been noticed to follow the storm-track in a direction contrary to that commonly noticed. The direction in which a true tornado _whirls_ is _invariably_ that I have mentioned. The explanation of this peculiarity would occupy more space than I can here afford. Those readers who may wish to understand the origin of the law of cyclonic rotation should study Herschel’s interesting work on Meteorology. The suddenness with which a true tornado works destruction was strikingly exemplified in the wreck of the steamship ‘San Francisco.’ She was assailed by an extra-tropical tornado when about 300 miles from Sandy Hook, on December 24, 1853. In a few moments she was a complete wreck! The wide range of a tornado’s destructiveness is shown by this, that Colonel Reid tells us of one along whose track no less than 110 ships were wrecked, crippled, or dismasted. (From _Temple Bar_, December 1867.) FOOTNOTES: [12] I remember to have read that in this hurricane guns which had long lain under water were washed up like mere drift upon the beach. Perhaps this circumstance grew gradually into the incredible story above recorded. [13] A ship by scudding before the gale may—if the captain is not familiar with the laws of cyclones—go _round and round_ without escaping. The ship ‘Charles Heddle’ did this in the East Indies, going round no less than _five times_. _VESUVIUS._