1859] WRITINGS OF JOSEPH HENRY. 441 



the many persons from a distance who visit the Institution 

 daily; all appear to be specially interested in knowing the 

 condition of weather to which their friends at home are sub- 

 jected at the time. But the value of the map is not confined 

 to the gratification of this desire. It enables us to study 

 the progress of storms, and to predict what changes in the 

 weather may be expected at the east, from the indications 

 furnished by places farther west. For example, if a black 

 card is seen in the morning on the station at Cincinnati, in- 

 dicating rain at that city, a rain storm may confidently be 

 expected at Washington at about seven o'clock in the even- 

 ing. Indeed, so uniformly has this prediction been verified, 

 that last winter the advertising in the afternoon papers of the 

 lectures to be delivered at the Institution that evening was 

 governed by the condition of the weather in the morning at 

 Cincinnati ; a rainy morning at the latter inducing a post- 

 ponement of the lecture. 



It must be evident, from the facts given, that if a system 

 of telegraphing over the whole country east of the Rocky 

 Mountains were established, information could be given to 

 the Middle and Eastern States of the approach of disturb- 

 ances of the atmosphere, — of much value to the agriculturist, 

 the ship-owner, and to all others who transact business af- 

 fected by changes of weather, as well as of importance to 

 the invalid and the traveller. Indeed, with a proper com- 

 bination of the lines now in operation, daily intelligence 

 might be obtained in the city of Boston which would be of 

 the highest interest to its inhabitants. [Professor Henry 

 mentioned Boston in particular, because this city is so situ- 

 ated that the storms, both of the southern and western class, 

 reach it after they have been felt in New York and in other 

 places which are not so far east and north.] It is necessary 

 to remark that the same use of the telegraph is in a measure 

 inapplicable to the inhabitants of Western Europe, since 

 they live on the eastern side of an ocean, and cannot be ap- 

 prised of the approach of storms from the west. For the same 

 reason the general laws of storms are more conveniently 



