102 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1925 



The experimental forecasts by Mr. H. H. Clayton for the city of 

 New York, mentioned in last year's report, were continued. For 

 this purpose daily telegrams of the condition of the sun were sent 

 from Washington to Mr. Clayton at Canton, Mass. These usually 

 reached him before noon on the day after the observations were 

 made in Chile and Arizona. Making up his New York forecasts 

 for three, four, and five days ahead, Mr, Clayton informed the 

 Smithsonian by letter on the same afternoon. On Friday of each 

 week he forecast the temperature departures for the ensuing week 

 beginning Sunday, and about the end of each month he forecast 

 the temperature departures for the ensuing month. These weekly 

 and monthly forecasts were also mailed in advance to the Smith- 

 sonian Institution. 



We have compared Clayton's forecasts with the events, using 

 mathematical processes of verification which are not susceptible of 

 personal bias. A moderate degree of foreknowledge is certainly in- 

 dicated, both for the specific forecasts of three, four, and five days 

 in advance, and for the more general average forecasts of weeks 

 and months. 



On May 2, 1925, a symposium on this subject was held at the 

 United States Weather Bureau before the American Meteorological 

 Society. At that time, Messrs. C. G. Abbot and H. H. Clayton ex- 

 plained the status of the measurements of solar variation, and their 

 applications for forecasting. Later, these papers of Abbot and 

 Clayton, and also a paper by INIr. G. Hoxmark, on the results 

 reached since 1922 in the application of solar variation for official 

 forecasts in Argentina, were published as Nos. 5, 6, and 7, of Volume 

 77, Smithsonian Miscellaneous Collections. 



The costs of telegraphic :idvices and of Mr. Clayton's computing 

 bureau have been borne by Mr, Roebling's gifts for these purposes, 

 as also the cost of publication of the papers just mentioned. 



No public forecasts have been made or will be made under the 

 auspices of the Smithsonian Institution. Our entire purpose in 

 the matter is, and has always been, to make such experiments as 

 might indicate what value, if any, would attach to the introduction 

 of a new variable, namely, the variation of the sun, in weather fore- 

 casting. Our forecasts arc made privately and onlj' as tests of the 

 experimental conclusions. 



Unfortunately, space writers in the public prints have not under- 

 stood this and have attributed to the Smithsonian Institution fore- 

 casts of weather conditions far into the future. These, in reality, 

 have been made by several private individuals entirely unconnected 

 with the Institution. We take no responsibility for these prognos- 

 tications, as we know as yet of no sound method by which they may 

 be made. 



