106 ANNUAL REPOET SMITHSONIAN INSTITUTION, 1922. 



Fourth, to try further experiments with the collection and storage 

 of solar heat for cooking purposes. 



The station on Mount Harqua Hala was visited by the director 

 and found in a highly improved condition owing to the zeal of Mr. 

 Moore, in charge there. The laboratory has been sheathed outside 

 with metal to protect the adobe walls from rain, and painted and 

 embellished within, lightning rods have been installed, a small shop 

 built, wireless telephonic apparatus erected, a garage built at the 

 foot of the mountain trail, and regular weekly mail and supply 

 trijDS arranged. Solar-constant observations have been made on 

 upward of 70 ]3er cent of the days of the year, and much computing 

 and testing attended to. Comparisons made during and after the 

 director's visit show no change in the scale of pyrheliometry, so 

 that as far as this is concerned the results at Harqua Hala are com- 

 parable with those at Montezuma. But from lack of sensitiveness 

 of the galvanometer the energy curves show less detail at Harqua 

 Hala, and this it was decided must be corrected as early as possible 

 to put the two stations on parallel footings. 



In conversation with Mr. Moore, the director devised a new im- 

 provement of the " short method " which, it was agreed, would pro- 

 mote accuracy while greatly abridging computation. This will be 

 introduced at both stations as soon as the new determination of the 

 form of the solar energy curve outside the atmosphere is worked out. 



At Mount Wilson, the time before the end of the fiscal year, June 

 30, only sufficed for a partial installation of new "solar constant" 

 apparatus replacing that which in 1920 was removed to Harqua 

 Hala. But it may be said by anticipation that later results were 

 secured on the distribution of energy in the spectra of 11 of the 

 brighter stars by bolometric work in connection with the 100-inch 

 telescope, and also that the solar energy curve was traced bolo- 

 metrically with both glass and rock-salt prisms. With the latter, 

 experiments were made at wave lengths from far down in the ultra- 

 violet to an infra-red wave length of 14 microns, with allowance for 

 stray light and for atmospheric and instrumental transmission. 



Unfortunately the cover of the oil reservoir of the solar cooking 

 apparatus had been blown oflf in a very high wind, and snow hav- 

 ing gotten in, much water had leaked into the oil reservoir. After 

 a long time of fruitlessly attempting to boil out this water, the oil 

 and water were at length removed, but not in time to undertake the 

 proposed new experiments before the return of the expedition to 

 Washington in September. 



OPINIONS OF THE SOLAR RADIATION WORK. 



As the Institution is making great efforts to continue and to im- 

 prove its solar-radiation measurements, the director felt concerned 

 to invite the opinions of competent critics, in order to know if these 



