SOLAR RADIATION ABBOT 197 



notable case of solar change, for the outstanding character of the 

 given solar change resulted from the superposition of several peri- 

 odic changes. Owing to differing lags, these periodic changes must 

 induce weather changes at various later times, which are not super- 

 posed, and are, therefore, inconspicuous. 



BY-PRODUCTS OF SOLAR-RADIATION WORK 



The atmospheric transmission at about 40 wave lengths has been 

 determined on thousands of days at many stations, including Wash- 

 ington, Bassour, Hump Mountain, Mount Harqua Hala, Mount Bruk- 

 karos. Mount Wilson, Table Mountain, Mount Montezuma, and Mount 

 Whitney, ranging in elevation from sea level to 4,400 meters. 



From the measured atmospheric transmission coefficients, Mr. Fowle 

 has determined the number of molecules per cubic centimeter of gas 

 at standard conditions. His result agrees perfectly with those 

 obtained by other methods. 



Mr. Fowle has developed a spectroscopic method of estimating the 

 thickness of precipitable water equivalent to the water vapor con- 

 tained in the atmosphere. This quantity is computed on all days 

 when solar-constant values are determined. 



Two methods of determining the quantity of atmospheric ozone 

 from holographic observations of the visible spectrum have been de- 

 veloped. Their results run parallel to those of Dr. G. M. B. Dobson. 



SUMMARY 



I have been dealing with the intensity of the energy of the sun's 

 rays; its losses in the atmospheres of the sun and the earth; its in- 

 equality over the solar disk; its distribution in wave lengths in the 

 spectrum; the development of instruments and methods to measure 

 these phenomena; the variability of the solar radiation; periodicities 

 in solar variation; and the dependence of weather thereon. These 

 wide-ranging yet closely related researches have engrossed my col- 

 leagues and myself for more than a quarter of a century. They have 

 yielded the following results, 



1. Improved stability and sensitiveness of the recording spectro- 

 bolometer. 



2. Accurate values of the dispersion of rock salt. 



3. Mapping of about 1,500 lines and bands of solar and terrestrial 

 absorption in the infra-red spectrum. 



4. Development of the silver-disk, the water-flow, and the water- 

 stir pyrheliometers, which have enjoyed wide acceptance. 



5. Improvement of the fundamental process of solar-constant 

 measurement. 



