(46 ) 



the mean value of the two determinations. As a test 30 other deter- 

 minations of latitude have been made with an instrument temporarily 

 adjusted for Talcott observations, from which I derived as mean 

 value: r/ =r 40°49' 14".8. The height above the sea-level is 55 meters. 

 The instrument at my disposal for the eclipse observation was a 

 new e(iuatorial of Mailhat (Paris), 2"^. 40 focal length and 16 cm. 

 aperture, provided with an eye-piece with a double micrometer. 

 I have determined the screw value of one of the two screws from 

 18 transits of circumpolar stars near the meridian. 1 found for it: 



i?j z= 60".3534 ±0".0117; 

 the value of the other screw was determined by measuring the 

 intervals by means of the first: 



i2^ =: 1.00010 . 72,. 

 The observatory possesses a good sidereal clock, the rate of which 

 had been carefully determined during four months by means of star 

 transits. In the night of 29—30 August, Mr. B. Berloty, a clever 

 observer had observed 20 clock-stars, so that the accuracy of the 

 determination of the clock-error left nothing to be desired. 



During the phase observations the object-glass was reduced to 

 25 mm. by means of a screen of pasteboard. The eye-piece with 

 a power of 30 was provided with a blue glass. The observations 

 of the chords were continued as long as was allowed by the field of 

 view of the eye-piece, which was more than 20' in diameter. At my 

 signal "top" the moments of the observations were noted by Mr. Belda, 

 who was seated in front of a mean time standard clock, which 

 before, during, and after, the observations was compared with the 

 sidereal clock; another assistant recorded the micrometer readings. 

 During the beginning and the end of the eclipse the sky in the 

 neighbourhood of the sun was perfectly clear, so that I could per- 

 form the measurements of the chords undisturbed, although now 

 and then I met with difficulties owing to irregularities in the rate 

 of the driving clock. From some minutes before, until after, totality 

 the sun was covered with light clouds, yet the moments of contact 

 could be recorded with sufficient accuracy. 



In the dei'ivation of the results I have taken the solar parallax 

 = 8". 80 ; for the rest I have borrowed the constants from the public- 

 ation "Observatorio Astronomico de Madrid. Memoria sobre el eclipse 

 total de Sol del dia 30 de Agosto de 1905". They are: 



Mean radius of the sun R, — 15'59".63 (Auwers) 



,, ,, moon ro = 15'32".83 (KuESTNEKandBATTERMANN) 



Parallax of the moon nr„ = 57' 2". 68 



