METEOROLOGICAL CORRESPONDENCE. 403 



Remarks. — The difference between the evapoiation from salt and fresh water 

 is readily shown by covering the bulbs of two thermometers with linen cloth, and 

 wetting one with salt and the other with fresh water. The reduction of tempera- 

 ture will be greater with the latter than with the former, provided the wetting be 

 renewed from to time to time ; but if the two linen envelopes be suffered to dry, 

 the one to which the salt water it> applied will continue wet the longer, and thus 

 indicate towards the end of the experiment a lower temperature. 



Although the difference of evaporation of salt and fresh water is apparently very 

 obvious, yet it has been asserted by a distinguished meteorologist that the covered 

 bulb of a thermometer sinks to the same degree whether wet with salt or fresh 

 water, and the evaporation from the sea is the same as from fresh water lakes ; 

 but this, as we have seen, is not correct. 



From the same. 



January 8, 1857. 

 A most strange phenomenon occurred on the last days of last month. Large 

 streaks and Helds of fresh water Avere discovered in the bay to the north and 

 northwest of this island. The water was of dark color, but otherwise clear, 

 and so fresh that many drank of it. At the same time toadfish, eels, snakes, 

 &c., which always inhabit salt water alone, came on shore in great numbers, 

 dead and dying. For a time the existence of fresh water was not believed, the 

 death of the fish being ascribed to the norther of the 22d and 23d of December; 

 but foiu- days ago fresh water Avas reported in the harbor of Key West. I ex- 

 amined, and found, at the last of the ebb-tide, water at 2i'^ Beaumer all along 

 the wharves. At one place it was 3°, and when I got home I tried the water at 

 my salt house, two miles distant, and found it 5°. The day before at salt house 

 it was 4*^. Evidently the water was fresher in the harbor the day before I tried 

 it. I am continuing the examination, and will write you again. What is the 

 cause of this ? Westerly winds could not have deflected the waters of the Mis- 

 sissippi, Alabama, &c., here. Have not the waters of the Everglades, which 

 have been very high for a year past, found cavernous outlets through the soft 

 lime rock into the bay ? This rock underlies the entire bottom of the Ever- 

 glades. 



From Rev. C. Dewey, Rochester, N. Y 



May, 1857. 



I think more attention ought to be paid to observations on the winds. It only 

 needs a thought to convince us that the clouds alone can show the general cur- 

 rent of the wind, and that the vane shows merely the ixnder and local currents. 

 The charts of some storms show a wonderfully strange direction of the wind in 

 some parts of our State; the reason is that the surface winds are those which are 

 exhibited. 



The attention is directed more at this time to the upper winds, 1 know, and 

 have no doubt that the direction of the wind in this State, and even New Eng- 

 land, in Professor Cuffin's admirable expositions of the winds in the Smithsonian 

 Contributions, will lie found not to correspond with the results obtained from ob- 

 servations for the next twenty years. There is too much reliance by observers 

 now, I fear, on surface winds. 1 should rather give up the wind vane and direct 

 tlieir eyes above and below ; the difference may not be great, but too much for 

 the designed accuracy of results now and in the future. 



IiEMARK.s — AVe fully agree with our much esteemed correspondent, whose re- 

 marks on any branch of meteorology are entitled to special attention, as to the 

 importance of observations on the motion of the clouds, upper and lower, in de- 



