B. TERRESTRIAL PHYSICS AND METEOROLOGY. 67 



observed during north polar expeditions and other short pe- 

 riods, in order thus to obtain normal annual means, when we 

 have primarily determined, at least approximately, the form 

 of the isothermal lines for the epoch of the observations. 



In connection with the preceding, Mr. Dove has made a 

 study of the cold days of February, the so-called February 

 minimum, for a number of European stations, and has shown 

 that this, in Europe as in America, probably results from a 

 cold polar current of air. Monatsherichte^ R. Akad. Berlin^ 

 September and October^ 1872. 



EAIJSr-FALL IX JERUSALEM. 



Dr. James Chaplin, who is at present residing in Jerusa- 

 lem, corrects a statement that the rain-fall there for 1863-64 

 amounted to but 8.84 inches, the actual quantity being some- 

 thing: over 19 inches. The error arose from the use of an im- 

 perfect rain-gauge, and has been corrected from other obser- 

 vations. 



In reference to the sirocco, he remarks that this is one of 

 the most frequent evils, being especially prevalent in the 

 month of May, and again in September, October, and Novem- 

 ber, just before the setting in of the rains. Its peculiarly 

 depressing effect he considers to be due to the entire absence 

 of ozone, the most careful observations, both of dry paper and 

 that which had been moistened, failing to indicate any discol- 

 oration of the ozone paper. Quarterly Statement^ Jan.^ 1873. 



EAIX-FALL IX THE UXITED STATES. 



The extensive work on the rain-fall in the United States, 

 lately published by the Smithsonian Institution, will be in- 

 valuable to engineers and others to whom are referred the 

 great questions of improving the navigation of the rivers of 

 this country. By means of such tables as are given in this 

 volume, a few minutes' computation enables one to determine 

 the area of country that must be drained in order to secure a 

 water supply sufficient for any specified purpose. The engi- 

 neers of Europe have long been sensible of the great practical 

 value of works of this nature, and we have before us a chart 

 of the rain-fall of Switzerland, showing, by carefully drawn 

 isohyetals, the minutest detail of the annual precipitation 

 (including the melted snow of winter). The construction of 



