148 PHILOSOPHY OF STORMS. 



designated by the figures, 0, 1 3 2, 3, 4, 5, &c. : signifying 

 entire cloudiness; 1, a very small portion of clear sky ; 

 and 10, entire clearness. To save room, the numbers ex- 

 pressive of clearness may registered in the same column 

 with the barometrical observations. For example, if the 

 barometer should be at 30.10, and the sky half clear, or 5, 

 this should be marked, in the column headed " barometer, 37 



30.10 

 5 ' 



Rain Guage. The rain guage should be placed in some 

 position near the ground, where it will receive the rain, let 

 the wind blow from whatever direction it may. The height 

 of this instrument, above the ordinary level of the ground, 

 should be mentioned in the first monthly report. As soon 

 as possible after a rain, the water collected in the receiver 

 should be measured in the glass tube, which is graduated, 

 so as to read to thousandths of an inch of rain falling into 

 the guage. In cold weather, the receiver may be surrounded 

 with straw, to prevent the water from freezing immediately. 



Where the precipitation consists of snow, it is usual to 

 estimate one foot in depth as equal to one inch of water. 



General Observations. Under this head should be noted 

 all remarkabe phenomena which cannot be inserted in the 

 regular columns, such as any sudden change of wind or 

 temperature ; times of clouding, with the varieties of clouds 

 prevailing through the day ; halos, auroras, fogs, thunder 

 storms, near or remote, silent lightning, with its direction 

 and elevation above the horizon, &c. 



Hints to Observers on Meteorology. 



118. The legislature of the State of Pennsylvania, at 

 their last session, appropriated four thousand dollars for the 

 advancement of meteorology, and out of this sum, which 

 has been placed at the disposal of the Joint Committee on 

 Meteorology of the American Philosophical Society and 

 Franklin Institute, a barometer, two common thermometers. 



