HOW TO AVOID HUEEICANES. 293 



he may suddenly find himself within the fatal circle, and be lost with 

 his ship, from having lacked the necessary boldness. In the high 

 latitudes of ocean it is easier to make a decision, and escape from 

 the cyclone, since the sea is open in the direction of the pole, and the 

 sailor has not to dread being completely enclosed in the midst of a 

 circle of tempests. It is behind him that the lower part of the 

 immense wheel ploughs the waves, before him the ocean is open, or at 

 least the winds which traverse its surface are produced by local causes, 

 and do not belong to the terrible storm. Only at very rare intervals 

 is the upper part of the cyclone brought down to the surface of the 

 water by violent atmospheric counter- currents coming from the polar 

 regions. In thirteen years the Dutch savants have only observed 

 two cases of this nature. 



Thus the hurricanes themselves, like the other manifestations of life 

 on our globe, have a regular course, and mathematicians can attempt 

 to calculate the orbit of these terrible phenomena over the face of the 

 earth. It is by conforming to laws and following spirals traced 

 beforehand that the revolving tempests are propelled from the 

 equinoctial zone to the temperate regions. Far from causing by their 

 violent spirals a permanent disturbance in the air, they, on the con- 

 trary, only re-establish the equilibrium between the unequal waves of 

 the atmospheric ocean. Still more, they aid conjointly with the mon- 

 soons and the counter trade-winds, to maintain the astronomical 

 equilibrium of the planet. Thus, as Dove remarks, the continual 

 friction of the trade-winds, which the terrestrial rotation causes to 

 deviate incessantly towards the west, would doubtless end by retarding 

 the movement of the earth around its axis, if other aerial currents 

 proceeding in an opposite direction did not counterbalance the 

 retarding causes, and accelerate on their part the rotation of the earth 

 from west to east. Slight as may be the breath of wind compared to 

 the force of projection which causes the planet to revolve, it does not 

 the less contribute to the movements of the globe and to its harmo- 

 nious circles in the concert of the heavenly bodies. 



