Total Solar Eclipse of 1901, May 17-18. 



227 



The cameras were focussed on trees on a distant hill viewed through 

 blue glass, and gave satisfactory images. 



The programme of exposures was the same as that for the Dallmeyer 

 telephotographic camera, as follows : 



8 seconds, 16 seconds, 32 seconds, 120 seconds, 4 seconds, 2 seconds, 

 thus including one long exposure, and five others in geometrical 

 progression, it being intended to compare the polarised image on one 

 plate with the unpolarised image on the plate next before it in the 

 series. The Savart was to be set in accordance with the result of visual 

 observations of the atmospheric .polarisation, so that the bands due to 

 atmospheric polarisation should be obliterated. The first photograph 

 was made with an arbitrary setting of the Savart, and the setting 

 chosen was one that would give the coronal bands slightly inclined to 

 the sun's equator. In the event no atmospheric polarisation was 

 detected, and the Savart was left at the same setting throughout all the 

 exposures. Mr. Wallace made simultaneous exposures for these and 

 for the Dallmeyer telephotographic camera. 



Results. As in the case of the Dallmeyer telephotographic camera, 

 four photographs were obtained, standard squares being impressed on 

 each plate after the eclipse with a standard candle at 5 feet. 



Exposure for Exposure for standard 



corona. squares. 



No. 1 8 seconds 10 seconds and 5 seconds 



2 17 20 5 



,,5 4 20 5 



,,6 2 5 (one only). 



All the photographs with the Savart camera are good clean plates 

 and show marked polarisation of the corona. The following table 

 summarises the extensions of the coronal streamers in the unpolarised 

 images and of the bands in the polarised. 



Extensions expressed in Minutes of Arc from Moon's Limb. 

 P = Polarised Image. U = Unpolarised. 



R 2 



