26 INSTRUCTIONS FOR MAKING PILOT BALLOON OBSERVATIONS 



than 15 minutes of time has elapsed, a separate and complete mete- 

 orological observation will be made. The results of this meteorolog- 

 ical observation and the settings of the theodolite will be entered in 

 the respective spaces upon the data sheet, or Form No. lllOA-Aer. 



72. The next step is the selection of the proper color of balloon to 

 be used and its inflation, as previously described under paragraph 48. 

 The data relative to the type and weight of balloon are then entered 

 on Form No. lllOA-Aer. 



73. Timing of observation. — It is important in theodolite work that 

 the timing for the angle readings be accurate. A watch may be used 

 for marking the time, but it is not as satisfactory as some device 

 whereby a buzz or signal is given at minute intervals. Without some 

 such automatic signal, there is always a possibility of allowing the 



OFFICe STATION 



FIELD STATION 



£ 



OJITTEKieS 



(S)0Q)Q 





U D£r/1/L or BUZZER 



r/f/t/vsMirrc/f j^ ^loch CONNECT/ONS 



Fig. 11.— Telephone circuit with time signaler installed. 



proper reading second to pass by or even to miss a minute entirely. 

 The timing device or time signaler used in the Weather Bureau is 

 described in paragraph 74. 



If a lime-interval clock is not used it will be necessary to keep 

 close watch of the time, in which case the "warning" signal will be 

 called by the recorder about 5 seconds before the expiration of the 

 minute, or the "read," signal. Generally the balloon is released on 

 the full minute, therefore the "read" signal would occur at the six- 

 tieth second and the "warning" signal on the fifty-fifth second. 



74. Time signaler. — The time signaler consists essentially of a 

 single-register clock, buzzer, and two dry cells encased in a small 

 wooden box. Two electrical contacts are made 5 seconds apart 

 whereby a buzz or signal is given at the fifty-fifth and sixtieth second. 

 It is so arranged that the first buzz will be a little long and quite 

 loud, and the second buzz much shorter. The first buzz is known as 

 the "warning" signal and the second buzz as the "read" signal. 

 This "warning" signal will give ample time for the observer to center 

 the balloon and the recorder to prepare for the reading of the angles. 



As most of the stations of the Weather Bureau are equipped with 

 telephones, the timing device or time signaler is usually installed in 

 the telephone circuit, thus enabling both the observer and computer 

 or recorder to hear the signal. 



75. Installation of telephones with time signaler in circuit. — In 

 figure 11 is shown the wiring of the telephone circuit with the time 



