METEOROLOGY. 403 



be the case. He replied, that during his first wintering on the lake, 

 a violent northwest gale lasted several days, and the water so entirely- 

 disappeared from the north end of the lake, that it was difficult to 

 water the cattle ; that the northwest gale was succeeded by a high 

 wind from the south, when the water returned, and was heaped up at 

 the north end of the lake, from which it had disappeared. 



Another phenomenon which at first seems unaccountable, is really 

 of easy solution. The outlets of our large ponds are covered with 

 strong ice in the early winter, which is dissolved as the cold becomes 

 more intense, and they remain a long time free from ice; sometimes 

 all winter. The obvious reason is, that our large ponds are kept, by 

 the wind agitating their surfaces, from freezing, long after they have 

 been cooled below the freezing point. The water thus cooled passing 

 into a sluggish stream, is soon converted into ice: but as soon as the 

 cold has become sufficiently intense to counteract the agitation of the 

 water, the pond freezes, and the water issuing from it has acquired 

 nearly the temperature of the earth, and thaws out the stream issuing 

 therefrom. 



Anchor ice, which in very severe weather interferes so much with 

 the operation of the mills, is formed in streams cooled much below the 

 freezing point, but where a strong current prevents the regular forma- 

 tion of ice. In making salt, copperas, and in similar operations, 

 when the body is ready to pass from a fluid to a solid state, the process 

 is hastened by throwing a stick into the basin or vat, about which the 

 crystals immediately commence forming. The stones in the bottom 

 of the stream and the poles in the rack in a mill-race answer the same 

 purpose. The ice crystallizes upon them, and increases by agglomer- 

 ation, till the flow of water is greatly impeded in its course. Ice crys- 

 tals are formed in early winter, immediately beneath the surface of 

 moist ground, and shoot up two or three inches above the surface, and 

 are sometimes called anchor ice; but their formation depends upon 

 different causes. 



DIFFERENCE OF TEMPERATURE IN DIFFERENT PARTS 

 OF THE CITY OF ST. LOUIS, MISSOURI. 



BY A. FENDLER, 



It is a generally acknowledged fact that in one and the same neigh- 

 borhood, the temperature of the open country is somewhat lower than 

 that of the city, and it is chiefly on this account that the former is 

 preferred as a place of residence during the heat of the summer season. 

 But it may not be so well known that, within the boundaries of the 

 same city, "at stations not quite two miles apart, this difference of tem- 

 perature amounts frequently to 8°, 10°, or even 11|°, and that the 

 mean temperature of the year maybe 1°.4 higher in one place than in 

 the other. 



We find these facts among some of the results elicited on com pain 

 my meteorological registers for 1859 with those of Dr. G. Engelmann, 



