B. TERRESTRIAL PHYSICS AND METEOROLOGY. 101 



ature occur. The comparison between Krueger's formula and 

 that determined by Hallstrom, for the eleven years ending 

 1839, shows important constant differences, which Krueger 

 attributes partly to the fact that the two series of observa- 

 tions were made in two entirely different localities, and partly 

 to the fact that the series used by Hallstrom was not so com- 

 plete as that of Krueger. Krueger on the Mean Temperature 

 of Ilelsingfors. 



RAIN-FALL ON THE ISTHMUS OF PANAMA. 



We can form very little idea in our temperate latitude of 

 the amount of rain which falls in various tropical regions of 

 the world, and especially on the Isthmus of Panama. Ac- 

 cording to a recent article in the Panama Star and Herald, 

 the amount of rain-fall in 1871 was about 100 inches; but in 

 1872 it reached the enormous quantity of 170 inches, or some- 

 thing over fourteen feet. The most rainy month on the 

 Isthmus is October, and the least is April. In the mountain- 

 ous portion of Central America, during the month of October, 

 the day dawns clear over the sea, but is cloudy along the 

 tops of the distant Cordilleras, the wind blowing fresh from 

 the southwest ; but at mid-day the mountains are covered 

 with clouds, and a pouring rain begins to be precipitated 

 from them at 2 P.M. The waters deluge the plains, and ex- 

 tend to the sea-coast in a flood. The thermometer generally 

 falls during the rain from 84 to 80, or to 79 Fahr. It is as- 

 serted that the rains were formerly much heavier even than 

 now, so much so, indeed, that for the month of October the 

 people laid in provisions and firewood for two weeks. It has 

 been noticed, on parts of the Isthmus, that the change from 

 the wet to the dry season, and vice versa, is apt to be attend- 

 ed by slight earthquake shocks. 



SELF-RECORDING RAIN-GAUGE. 



The success of Professor G. W. Hough, of the Dudley Ob- 

 servatory, in constructing self-recording barometers and ther- 

 mometers, lends additional interest to his announcement of 

 the successful construction of an automatic evapometer and 

 rain-gauge. The apparatus consists of a vessel two feet 

 square and one foot deep, suspended on levers, and held in 



