38 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 'J'J 



yearly period, such as might have been expected from the results of 

 two observatories in opposite hemispheres of the earth. However, 

 the mean values of differences without regard to sign vary consider- 

 "ably from month to month, as would be expected. 



Both stations usually have unfavorable weather conditions in 

 December. January, and February, and at Harqua Hala these are also 

 prevalent in March, April, July, August and September. May, June 

 and October are the best months for duplicate observations, and if 

 Ave had two stations as favorable all the year around as our present 

 '.97r 



/.96 



I.S5 



o 2d 40 60 86 ToQ led ko JeO Jad Too 25o" 

 Fig. 2. — Increased solar activity brings higher solar-constant values. 



two appear to be in these months, there would be little better to ask 

 for. As conditions are, there is evidently great need of at least two 

 additional first-rate stations, making at least four of them under 

 common management, if really satisfying measurements of the sun's 

 changes are to be obtained. 



Unfortunately, the Smithsonian Institution has not the financial 

 means for this. It would require for each new station from $io,ooo 

 to $15,000 for original installation, and from $8,000 to $12,000 a year 

 each for continuous operation thereafter, depending on location. It 

 is probable that situations in Africa and in Asia should be chosen, 

 but before selecting them an expenditure of about $5,000 for pre- 

 liminarv investigations of sites should be made. 



