22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 76 



The last two weeks were spent in a brief study of certain sections 

 in the Wasatch and Bear Lake Mountains in Utah. These ranges 

 form the western edge of the great Rocky Mountains and offer many 

 compHcated problems in structure and stratigraphy. These mountains 

 are higher and consequently catch a heavier rainfall. The well-watered 

 strip, which is the rich agricultural district of Utah, is the result. 

 Cache Valley in the northern part of the state, between two ranges, is 

 densely peopled in its many farming communities and is a region of 

 great beauty. Numerous canyons have been cut by the larger streams 

 around this valley and among them is the Blacksmith Fork Canyon 

 studied some years ago by Dr. Walcott (see fig. 27), with results 

 which proved so interesting that further collections were desirable. 



FIELD-WORK OF THE ASTROPHYSICAL OBSERVATORY 



In 191 8, the Astrophysical Observatory began to undertake the 

 daily measurement of the variation of the sun. The late Secretary 

 Langley used often to express his prevision that the study of the sun's 

 heat, the losses which it suffers in passing through our atmosphere, the 

 variations which it may be subject to, would at length serve to fore- 

 cast the changes of weather and climate which are so important for 

 the agriculturist, and which in some parts of the world even lead 

 occasionally to periods of disastrous famine. He used to speak of 

 Joseph's seven years of plenty and seven years of famine, in this con- 

 nection, and of the possibility that in the future the student of the 

 sun might be in a position to emulate that ancient prophet. 



Langley's dream received some support when the Smithsonian 

 Astrophysical Observatory discovered the substantial variability of 

 the sun, and confirmed this discovery by its expeditions to Africa. 

 The influence of the solar variation on the weather was studied by 

 Mr. Clayton, at that time chief forecaster of the Argentine Meteoro- 

 logical Service, and he seemed to find that the sun's variations pro- 

 duced notable influence on the weather conditions of Argentina, and, 

 indeed, of the rest of the world. The results of these preliminary 

 studies of Mr. Clayton were published in the Smithsonian Miscel- 

 laneous Collections, Vol. 68, No. 3. and Vol. 71, No. 3. 



Our previous investigations had been restricted to the summer and 

 autumn seasons which are notably cloudless at our observing station 

 on Mt. Wilson, Cal. These results appeared so encouraging that it 

 seemed incumbent on us to make the necessary observations of the sun 

 throughout the entire year for a number of years, in order to make 



