XO. 27, CORRECTIONS TO SILVER-DISK PVRHELIOMETRY ABBOT / 



( Jlxservatory for 2=^ years, he would have heen kind enough to have 

 consulted me privately before publishing his conclusion. The pro- 

 longed hurtful influence of such an important erroneous publication 

 in the literature can never be overtaken by any subsequent correction. 

 However, copies of the present paper will be sent to all owners of 

 silver-disk pyrheliometers, and to many other individuals and insti- 

 tutions likely to be interested. 



I must add that since the work published by Iniessner on the absolute 

 scale of pyrheliometry is certainly vitiated so far as it depends on his 

 preferred reduction of the silver-disk pyrheliometer observations, and 

 was moreover of a character that permitted so erroneous a conclusion 

 to be derived as that which he has published, I cannot but feel that its 

 findings as to absolute pyrheliometry must be taken with great reserve. 

 It would be very desirable indeed if a direct comparison could be made 

 at Mount Wilson between the Smithsonian water-flow double-chamber 

 pyrheliometer No. 5. and the standard ))yrheliometer which was 

 employed by Fuessner. 



