§ 791, 792. STORMS, HUKRICANES, AND TYPHOONS. 423 



send by telegraph to Europe warning of many a one long before 

 it could traverse the Atlantic. The contributions which the mag- 

 netic telegraph is capable of making for the advancement of me- 

 teorology will enable us to warn the ships in our Gulf ports, as 

 well as those of Cuba, of the approach of every hurricane or tor- 

 nado that visits those regions. 



791. But, returning to the cyclone theory : though the wind 

 The changing of the ^^ blowiug around in spirals against the hands of 

 windinacydone. ^^^ watch, yct, froui thc fact that the centre about 

 which it is blowing is also traveling along, the changes of the 

 wind, as observed by a vessel over which the storm is passing, 

 will not, under all circumstances, be against the sun in the north- 

 ern, or with the sun in the southern hemisphere. The reason is 

 obvious. This point is worth studying, and any one who will re- 

 sort to '' moving diagrams'^ for illustration will be repaid with edifi- 

 cation. Piddington's horn cards are the best; but let those who 

 have them not cut a disc of paper of any convenient diameter, 

 say 2|- inches, and then cut out a circle of 2 inches from the mid- 

 dle ; this will leave a ring half an inch broad upon which to 



draw arrows representing the course of 

 /^^,_L_r >\ the wind. Suppose them to be drawn for 

 ^/^ ^"^X *^^^ northern hemisphere, as in the annex- 



ed diagram: lay the paper ring on the 

 chart ; suppose the ship to be in the KE. 

 quadrant of the storm, which is traveling 

 north, the storm will pass to the west, but 

 the wind will change from S.E. to S., and 

 so on to the west, loitli the hands of a 

 ivaich^ though it be revolving about the centre against the hands 

 of a luatch ; still the rule for finding the direction of the centre 

 holds good : Face the wind, and the centre in the northern hemi- 

 sphere will be to the right ; in the southern, to the left. 



792. Suppose that in the case before us the storm is traveling 

 The \vind stronger on to the Horth at the rate of 20 miles the hour, and 



one side than the oth- ■, ^ > ■\ > i . it i 



er. that the wind is revolving around the centre also 



at the rate of 20 miles the hour: when the vortex bears west 

 of the ship, the wind will be south. It is going 20 miles to the 

 north with the body of the storm, and 20 miles around the 

 centre ; total force of the wind, 40 miles an liour on the east 



