WEATHER FORECASTS. 



319 



circuit except for an instant each minute. When it is cloudy the 

 pen simjDly traces a straight line. 



The recording rain gauge consists of a cylindrical casing sup- 

 porting an open funnel above and a reservoir below. Beneath 

 the mouth of the funnel is a pivoted tray or " bucket " divided into 

 two compartments and pivoted so that it can be tipped to bring 

 one compartment under the funnel mouth; and, when that is filled 

 with rain water, it will be overbalanced and tip down, thus pouring 

 its water into the reservoir and bringing the empty compartment 

 under the mouth of the funnel. This tipping of the bucket momen- 

 tarily closes an electrical circuit including the sunshine-recording 

 magnet of the triple register, and causes the pen to follow a motion 

 in general like the sunshine record, but so irregular as to time, and 

 having either more or less steps in a given time according to the 

 rapidity of the rainfall, that it is 

 easily distinguished from the sun- 

 shine record. The clock does 

 not interfere with the circuit of 

 the rain gauge. 



As the atmosphere extends 

 upward some forty miles, it is 

 evident that observations made 

 at the usual height of a few score 

 feet can not give much idea of 

 the condition existing in the gen- 

 eral mass of air, and it is sur- 

 prising that such successful fore- 

 casts are made from these meager 

 data. For some time past 

 efforts have been made to 

 up recording instru- 

 by means of 

 kites or trains of kites. 

 The kite shown in Tig. 

 14 is a typical Weath- 

 er Bureau kite. Its 

 weight is but six 

 pounds, and yet it pre- 

 sents to the wind an area of fifty square feet, and has lifted a weight 

 of one hundred pounds in a wind of twenty-five miles an hour. An 

 altitude of seven thousand feet has been reached with the kites. A 

 special instrument is made for attachment to the kites that electrically 

 records the temperature, pressure, and humidity of the air and the 

 direction of the wind. The combined weight of the instrument and 



carry 



ments 



,/ 



Fig. 12. — The Recording Eain Gauge. 



