HUREICANES. 259 



is it so violent that the ship cannot weather it ? All these things must be 

 weighed well by the mariner, before he endeavours to lay his ship on that 

 tack which will appear the best to forward his voyage. Should the Storm 

 be advancing in the same direction as his course, and the position of the 

 ship be upon the anterior verge, should it travel at a rate above that which 

 he can keep up, it is evident that it will pass over him, and the consequence 

 need not be remarked upon. Should the vessel be upon the posterior verge 

 of the Hurricane, it will, if travelling at 20 or 30 miles an hour, soon leave 

 her, and then no advantage can follow ; and if the Storm be travelling 

 slowly, a vessel in this position might run into the heart of it, owing to the 

 great indraft of the winds, as explained in (155). 



Thus, to "make use of a Hurricane," several conditions are absolutely 

 necessary: these are — " 1. The ship must get into the Storm precisely 

 where the wind blows fair for the prosecution of the voyage — which is quite 

 a matter of chance. 2. If she happen to do so, she must, to derive benefit, 

 regulate her speed exactly to that of the meteor. Can she do that at 

 pleasure ? There would be no difficulty in ascertaining the fact of her pre- 

 serving her station, or not, by the wind remaining steady, or veering ; but 

 there is a necessity that would bind her, and which cannot be evaded with 

 impunity when a high sea follows ; she must carry a certain proportion of 

 sail to prevent her from being pooped. Now this sail may give her a 

 greater velocity than the meteor at the time ; hence she would run ahead 

 of it. Again, the rate of the meteor may be greater than her utmost speed; 

 hence she would be ejected." 



Again, as stated in (163), vessels, making use of the favourable wind on 

 the Eastern side of a Cyclone, must take steps to avoid the Storm at its 

 point of recurving from N.W. to N.E. A vessel steering to the Northward, 

 having the wind aft, may possibly keep up with the progress of the Hurri- 

 cane ; but on reaching its point of recurving would be in danger of havmg 

 the vortex pass over her. 



SQUALLS AND TORNADOS. 



(204.) Captain Andrew Livingston, of Liverpool, to whom we are in- 

 debted for much valuable information, gives the following description. 



'• Squalls are generally of three kinds. That called the Arched Squall is 

 frequently experienced, and usually rises from the horizon in the form of 

 an arch; but sometimes it assumes the appearance of a dense dark cloud, 

 particularly when highly charged with rain, or electric matter. From the 

 time that the arch or cloud is first seen above the horizon, its motion is 

 sometimes very quick to the zenith, the interval being scarcely sufficient to 

 allow a ship to reduce the necessary sail before the wind reaches her, which 

 happens when the cloud has approached the zenith. At other times the 

 motion of the cloud is very slow, and not unfrequently it disappears, or is 

 dispersed, the impulse of the wind being not then sufficient to reach a ship. 

 As a general rule, it may be observed, that if in these squalls there be rain 

 preceding the wind, the latter will probably follow the rain in sudden severe 



