106 ANXUAL REPORT SMITHSONIAN INSTITUTION, 1924 



ticular have proved very unsatisfactory. If financial means were 

 available it would be highly desirable to remove the station to 

 another site, and, indeed, a better one is already selected which 

 would present many advantages. The cost of removal would be 

 about $7,000. 



The systematic revision of results in the hands of Mr. Fowle and 

 Mrs. Bond has led to much improvement, as shown by the close 

 accord of daily solar-constant values at the two stations. For the 

 period September, 1922, to March, 1924, the average daily difference 

 is less than 0.5 per cent. In the month of October, 1923, when the 

 weather was fine at both stations almost every day, it ran as low as 

 0.2 per cent. 



The solar-constant values have continued almost without excep- 

 tion below normal. From March, 1922, until June, 1924, the meaa 

 result for every single month was below the normal value, which is 

 1.938 calories per square centimeter per minute. This long-continued 

 defect of solar radiation may well have produced interesting climatic 

 effects. It is interesting to report in this connection a letter from 

 M. Antoniadi, of France, stating that the polar cap of Mars is larger 

 than it has been under parallel conditions for 70 years, and asking if 

 the solar-radiation measurements showed anything unusual. Nat- 

 urally decreased solar radiation would tend to produce that effect. 



A letter from the eminent meteorologist. Doctor Bj crimes, of 

 Norway, to Doctor Hale, of the Mount Wilson Observatory, h:is 

 been referred to us, and with permission of the author is here copied 

 in part as an indication of expert appreciation of our work : 



I have been greatly interestocl in the establishment of a complete " cir- 

 cumpolar " weather service, as this only will give the full view of the changing 

 states of the atmosphere. This circumpolar service is now beginning to become 

 a reality. The charts may soon more or less cover the entire northern 

 hemisphere. 



But then another idea arises by itself, namely, to bring these more and more 

 complete pictures of the varying states of our atmosphere into connection with 

 their ultimate cause, the solar activity. * * * 



I am aware that the solar constant is determined every day at Mount Wilson 

 Solar Observatory, and at the Calama Observatory of the Smithsonian Insti- 

 tution. * * * I think it would now be of high importance to every day 

 have the most recent value of the solar constant incorporated in the daily 

 meteorological issue. 



If this should be practicable, the value of the data which are every day at 

 the disposal of the meteorologist would increase enormously. It is, of course, 

 dangerous to prophesy. But a new era may perhaps begin for meteorology 

 from the moment when the meteorologist has at his disposal every day com- 

 plete data both for the sun's activity and for the state of the atmosphere over 

 an entire hemisphere of the earth. 



Work at the two solar-radiation stations. — The results just dis- 

 cussed are, of course, the fruit of the zealous work of our observers in 



