Mr. H. F. Newall. 



and the second (17 seconds) shows very little more than the fifth 

 (4 seconds). 



The form of the corona is clearly of the type associated with the 

 minimum in the sunspot cycle. 



The eastern equatorial region shows great disturbance, and there are 

 many striking prominences on the eastern limb and several marked 

 arches. In particular, reference may be made to (i) two dark rifts 

 radiating from the neighbourhood of a prominence near the sun's 

 equator, on the east side ; (ii) bright and dark arches in no less than 

 three of the quadrants, extending about 4' from the limb ; (iii) a dark 

 region surrounding a large prominence whose position-angle is approxi- 

 mately 20 measured from the X. point of the sun ; and (iv) a remark- 

 ably definite edge as of a chromospheric layer for a considerable arc of 

 the sun's limb, in the N.W. quadrant, such as Sir Norman Lockyer 

 described as seen in the photographs secured in Spain last year. 



A summary is given below of the extension noted in the different 

 photographs extension being measured beyond the moon's limb, and 

 expressed in minutes of arc : 



^13. The Polariscopic Camera (Savart Plates and Nicol Prism}. 



The Savart camera, which was constructed for use in Algiers, was to 

 be used on the present occasion with a view to getting information as 

 to the amount of polarisation in the outer regions of the corona, and, 

 in particular, in the search for the position of maximum polarisation. 



Professor J. J. Thomson very kindly put the large Nicol prisms 

 from the Cavendish Laboratory collection at my disposal again, and the 

 Savart plates were arranged in the same way as last year.* 



The camera was put in the second compartment of the double 

 tube, side by side with another camera which was provided with a 

 similar lens, but had no polarising apparatus in front. In this way 

 images of the same scale were obtained side by side on the one plate, 

 one image being taken through the polariscopic camera, the other 

 through the plain camera, each camera having an aperture approxi- 

 mately F/27. 



* ' Proc. Koy. Soc.,' vol. 67, p. 363 ; ' Monthly Notices, Roy. Astro. Soc.,' TO!. 60, 

 App, p. [27]. 



