NO. 2 



SMITHSOXIAX EXPLORATION'S, I918 



29 



measurements being made at Calama, Chile, under the direction 

 of ]\Ir. A. F. ]\Ioore, assisted by ]^Ir. L. H. Abbot. The outfit there 

 is the same that was used by them during the previous year at Hump 

 rvlountain. in North CaroHna. The present station was chosen as 

 the most cloudless one to be found upon the earth, and they have been 

 able to observe about 75 per cent of the da_\-s since the 27th of July, 



Fig. 28. — The Coelostal, Pvrheliometers, and Theodolite. 



Fk;. 29. — Part of the Spcctro-Rolometer. 



when the measurements Ijegan. I'or long ])cri()(ls ol time, as. fur 

 examijje, the period from the nn'ddle <jf .XoNcmhcr lo the middle of 

 December, there was not a single day lost, although this re(|uired 

 that the sky should be perfectly cloudless for about three hours. 

 either in the early morning or the late afternoon. Xotwithstaiidiiig 

 the Laeat number of favorable da\s for the observations, the records 



