28 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 68 



Valuable work has been done with the pyranometer on the bright- 

 ness of the sky, the quantity of radiation available to vegetation in 

 the forest, and on nocturnal radiation. This work will also go on 

 throuQfh the winter, including measurements on snow fields, and the 



Fig. 27. — The coelostat for reflecting 

 sun-rays. 



Fig. 28. — A. F. Moore reducing observations with 

 sHde-rule machine. 



investigation of certain errors likely to be made in nocturnal radia- 

 tion work. 



It is to be hoped that the expedition will yet be transferred to 

 northern Chile. In that region where rain scarcely ever falls, winds 

 never rise above the gentlest breezes, absolutely cloudless skies pre- 



