440 WKITINGS OF JOSEPH HENRY. [1859 



Gulf of Mexico, and passing onward it was felt in Guate- 

 mala on the 10th. While it was advancing southward it 

 was spreading over the continent to the east ; on the 7th it 

 reached the Red River settlement and all places under the 

 same meridian, down to the Gulf of Mexico. It reached the 

 meridian of Chicago on the 8th, the western part of the State 

 of New York on the 9th, New England on the 10th, and Cape 

 Race on the 13th. It moved with about equal velocity over 

 the Southern States and was observed at Bermuda on the 

 12th. 



The remarkable frost of last June, so far as it has been 

 traced, had the same origin and followed the same eastward 

 course. The fact was also illustrated, (by the maps before 

 mentioned,) that the warm periods which have occurred in 

 past years have followed the same law of progression, and 

 consequently their approach could have been announced to 

 the inhabitants of the Eastern States several days in advance 

 had a proper system of telegraphic despatches been estab- 

 lished. 



The value of the telegraph in regard to meteorology has 

 been fully proved by the experience of the Smithsonian 

 Institution. The Morse line of telegraph has kindly fur- 

 nished the Institution during the last twelve months, free 

 of cost, with a series of daily records of the weather from 

 the principal stations over the whole country east of the 

 Mississippi river and south of New York. In order to ex- 

 hibit at one view the state of the weather over the portion of 

 the United States just mentioned a large map is pasted on a 

 wooden surface, into which, at each station of observation, a 

 pin is inserted, to which a card can be temporarily attached. 

 The observations are made at about seven o'clock in the 

 morning, and as soon as the results are received at the Insti- 

 tution, an assistant attaches a card to each place from which 

 intelligence has been obtained, indicating the kind of weather 

 at the time; rain being indicated by a black card, cloudiness 

 by a brown one, snow by a blue one, and clear sky by a 

 white card. 



This meteorological map is an object of great interest to 



