ADVISORY COMMITTEE ON ASTRONOMY III 



large object, and I was led to write you what is in substance the 

 following letter: 



I learn from yours of February 14 that you would like to call it 

 to the attention of the Executive Committee of the Carnegie Insti- 

 tution, and, as I have written, I shall be very glad to have you do 

 so, asking you to make it clear that it is in no way a request from 

 the Smithsonian Institution, but a suggestion from me of a great 

 object which Mr. Carnegie himself may care to take up. 



I do so the more readily because, considering the Institution 

 wholly apart from its own needs, it would be the glad means of 

 indicating to those who wish some worthy aim for expenditure, 

 some specific object, which may be undertaken if desired in their 

 own name and through any worthy medium they prefer. 



One of these is the determination of the heat the Sun sends the 

 Earth and the causes of its probable variation. The progress of 

 solar physics has been such in the last few years as to make it of 

 interest to every inhabitant of the planet that this progress should 

 be carried further, not only in scientific, but in economic, and in 

 even humanitarian interests. 



The establishment of a great observatory in the tropical or sub- 

 tropical regions at a high altitude would advance our knowledge of 

 the heavenly bodies in a degree more than could be done by all the 

 ph3^sical observatories in the world united. To the founder of such 

 an observatory there would be enduring fame, but it is an affair of 

 a very great deal of money, possibly to be reckoned only in millions. 

 The establishment and maintenance for eleveu years of a distinctly 

 solar observatory under these conditions would enable us to study 

 the sun as it has never yet been studied, and through an entire solar 

 cycle, for much less cost. 



While this latter research, then, is to be pursued at less cost than 

 the foundation of a great general observatory, it has a specific object 

 of literally world-wide importance and interest. 



The determination of the heat the Sun sends the earth annually is 

 the determination of that through which everything on the planet 

 lives and moves, and almost unknown slight variations of this heat 

 are the probable, if remote, cause of the changing character of the 

 seasons and of the lack or plenty in the crops upon the Earth as a 

 whole. 



It has seemed possible within the last few years that if we had 

 this knowledge, the j^ears of plenty and of famine could be forecasted 

 as we now forecast a coming storm through the advices of the 



