I O O <^ 3 b 



THE APPARENT PROJECTION OF STARS UPON 

 THE BRIGHT LIMB OF THE MOON AT 

 OCCULT ATION, AND SIMILAR PHENOM- 

 ENA AT TOTAL SOLAR ECLIPSES, 

 TRANSITS OF VENUS AND 

 MERCURY, Etc., Etc. 



BY GEORGE DAVIDSON, PH.D, SC.D. 

 Jiead before the California Academy of Sciences^ August 9, i8gj. 



CONTENTS. 



Page. 



Introduction 64 



Geodetic Observations in the Sierra Nevada 66 



Visibility of Jupiter's Satellites 66 



Conditions of Steadiness and Unsteadiness of the Atmosphere 67 

 Observed Occultations of Red Stars at the Bright Limb of 



the Moon 73 



Other Observed Occultations of Stars by the Moon, and of 



Stars and Satellites by Jupiter 75 



Similar Phenomena at Total Solar Eclipses 81 



Similar Phenomena at Transits of Venus and Mercury Across 



THE Sun's Disc 82 



Instructions for Observing the Transit of Venus 85 



Curious Descriptions of the Phenomena 87 



Errors of Observation 88 



Observations of Solar Eclipses under Different Atmospheric 



Conditions 89 



Graphic Exhibition of Unsteadiness 92 



Official Recognition of the Factitious Borders of the Moon 



AND Sun 93 



Great Elevations for Observation 94 



Precision Observations at Low Elevations 96 



Recapitulation of Phenomena at Observation 97 



Other Important Results Affected 100 



Nearly All Measured Diameters Too Larg e loi 



[63] November 15, 1900. 



an 



