SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 87, NO. 15. PL. 1 





1. Water-flow pyrheliumeter No. 5 

 disassembled. 



2. Water-flow pyrhelionieter No. 5 

 assembled. 



3. L. B. Aldrich reading silver-disk pyrheliometer S.I. 51. is as mounted with 

 water-flow pyrheliometer Xo. 5 lor comparison. 



