122 PROCEEDINGS OF THE CALIFORNIA 



Synnestvedt, 1869, 1 v. 4to.; Oscarshalle, pam. 4to.; Forstelling om Thomas a 

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 pam. 8vo. Bull, de la Soc. des Sciences de Neuchatel, vol. VIII., 1868, 1 v. 

 8vo.; Mem. de la Soc. de Physique et d'histoire Nat. de Geneva, vol. XX., pt. 1, 

 1869, 4to.; L'Epoque quaternaire dans la vallee du Po, 1864, pam. 8vo., 

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Prof. Davidson mentioned the remarkable effect of the sun's heat 

 on the sandstone bluff seventy feet high, on which his instruments 

 were placed for observations, near San Buenaventura. The expan- 

 sion caused by the greatest heat of the day produced a serious 

 change in their level, and obliged him to move the instruments one 

 hundred yards back, when the disturbance ceased. 



He also remarked that the inhabitants of the southern plains of 

 this State were likely to lose their entire crops from trusting too 

 much to rain, when they could obtain abundant water for irrigation 

 at seventy feet depth. 



He also exhibited about one hundred photographs of the late 

 total eclipse of the sun, taken at Springfield and Shelbyville 

 Illinois, showing the improvement in accuracy of observations by 

 photographing them. 



The Professor then stated that in observing the occultation of the 

 star Alpha Scorpii by the moon, the o'ed star seemed visible for 

 some seconds on the grey limb of the moon, although ])ale stars 

 disappear at the moment of contact. No satisfactory explanation 

 of the phenomenon has yet been given. 



Dr. Cooper' suggested that the image of a red star was likely to 

 remain on the retina, and therefore seem visible longer than that of 

 a pale one. He also gave an account of some observations made 

 by him in a late trip in the Sierra Nevada, on the absence of frost 

 in the ground under the deep snow, and on the wonderful rapidity 



