NO. 9 SOLAR ECLIPSE I918 ALDRICH 5 



For the determination of the times of contact, a small telescope of 

 2 inches (5 centimeters) aperture was mounted just outside the 

 opening in the barn. 



ASSIGNMENT OF OBSERVERS 

 The observers were assigned as follows : 

 Rev. Woodman, 



( 1 ) Determination of times of contacts and general observations 



with the 2 inch refractor. 



(2) Giving of warning signals. 



(3) Manipulation of the cap exposing the photographic plates. 

 Mr. Kramer, 



(1) Manipulation of the pyranometer. 



(2) Observations of general phenomena. 

 Mr. Aldrich, 



( 1 ) Observing at the galvanometer. 



(2) Manipulation of the camera driving mechanism and plate- 



holder slides. 

 A number of practise eclipses were carried through on Saturday 

 morning to familiarize each with his duties. 



OBSERVATIONS 



(i) PYRANOMETER 



Observations with the pyranometer both of the brightness of the 

 sky alone and of the total sky and sun, were made on the afternoon 

 of the eclipse beginning at about one o'clock of local summer time 

 and continuing until after ten o'clock at night. These were made 

 about every 15 minutes up to the beginning of the eclipse, their fre- 

 quency then increasing as totality approached and again decreasing 

 after totality. An observation of the brightness of the sky was made 

 2 minutes before totality and 15 seconds after totality, and of the 

 total sky and sun 2.\ minutes before and 1 minute after. During 

 totality the glass hemisphere covering the pyranometer strip was re- 

 moved and two determinations made of the outgoing radiation to 

 space. In the course of the observations frequent calibrations were 

 made with heating currents sufficient to give deflections of the same 

 size as those recorded by the exposures to the sky and to the sky and 

 sun. Also, at intervals readings were made of the water vapor pres- 

 sure with a sling psychrometer. 



