254 



SCIENCE. 



[Vol. XIII. No. 322 



coil or band 5. When the coils or circuits S and C are separated, 

 as in Fig. 7, a closed iron path for the core /, as indicated by the 

 arrows, is afforded the iron /' ", operating after the manner of an 

 armature, and comes into play to increase the effective self-induc- 

 tion of the coil C. Elihu Thomson. 



WEST INDIAN HURRICANES. 



The Bay of North America is that portion of the North Atlantic 

 west of the 50th meridian, between Newfoundland and Venezuela, 

 including the Caribbean Sea and Gulf of Mexico. In accordance 



the higher latitudes. West Indian hurricanes follow this path 

 with marked regularity ; so much so, that a hurricane reported off 

 Antigua or St. Thomas is almost sure to either sweep across the 

 Greater Antilles into the Gulf of Mexico and strike our Gulf coast 

 with furious intensity, or else (according to the time of the year) 

 cross the Bahamas and follow the Gulf Stream toward Hatteras 

 and the Grand Banks. With the telegraphic facilities that already 

 exist, it is therefore possible to give from twenty-four hours to ten 

 days' warning of the approach of one of these terrific tropical 

 cyclones, — warning that might often result in the saving of more 

 property ashore and at sea in a single storm (not to speak of the 





TELEGRAPH CHART 

 OFTHE 



BAY OF NORTH AMERICA 



■:.— 'f]ie scale of this Wiart Iwi'j^ smjiU, but few of the ports of tlie Un 

 u-itli tfclt'Knipliic facilitini li:;vo l«cu indicated. Every port of the sligii 



with the policy followed hitherto by the United States Hydrographic 

 Office, of caUing attention to matters of special importance to 

 navigators, on " The Monthly Atlantic Pilot Chart," a telegraphic 

 chart, which we here reproduce, has been prepared to illustrate 

 the admirable facilities that are available for the establishment of a 

 more complete system of telegraphic weather forecasts, for the 

 benefit of the commerce of various nations frequenting this great 

 bay, as well as of the inhabitants of its shores and islands. The 

 general movement of storms over this area is westward in the 

 tropics, then northward into the temperate zone, and eastward in 



lives endangered) than would suffice to pay for the cost of a well- 

 equipped weather service for several years. Moreover, it is well 

 known that the movement of an area of low barometer is controlled 

 to a very large extent by areas of high barometer adjacent to it, 

 especially in advance (even though a thousand miles away), and 

 many noticeable instances might be referred to : the hurricane in 

 the Gulf in August, 1886, for example; the March blizzard of last 

 year ; and the severe cyclone off the coast last November. The 

 wider the field of observation, therefore, the better the forecast ; 

 and the completion of the cable to Bermuda will be invaluable in 



