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IV. Observations of the Corona during the Total Eclipse, August 7, 

 1869. By G. K. Winter, Telegraph Engineer, Madras Rail- 

 way Company, Arconum, 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



IN the October Number of the Philosophical Magazine there 

 is an article by Professor Pickering entitled "Obser- 

 vations of the Corona during the Total Eclipse, August 7th, 

 1869." As the results obtained by Professor Pickering by 

 means of the double-image polariscope are directly at variance 

 with the experience of myself and others during the eclipse of 

 August the 18th, 1868, 1 hope a few remarks upon the subject 

 may be deemed worthy of your acceptance. 



In August 1868 I accompanied Mr. Pogson (the Government 

 Astronomer at Madras) to Masulipatam, to assist him in ob- 

 serving the now celebrated eclipse of that year. My special 

 duty was to test the light of the corona and red flames for pola- 

 rization. .For this purpose I was provided with a Savart's pola- 

 riscope, and a double-image prism with a plate of quartz cut per- 

 pendicularly to the axis. Each of these polariscopes was adapted 

 to an excellent telescope by Cooke and Sons, 2V aperture and 

 28" focal length. 



On examining the light from the corona by means of the 

 Savart's polariscope, I found it very strongly polarized every- 

 where in planes radial to the sun's centre. The bands were ex- 

 tremely vivid near the moon's limb, and faded off with the co- 

 rona. There was very little light, polarized or unpolarized, beyond 

 the limits of the corona ; so that the explanation that the po- 

 larized light seen by some observers was derived from the atmo- 

 sphere illuminated by the unobscured portions of the earth is, I 

 think, untenable. Several portions of the corona were succes- 

 sively tried ; and in all the white central bands were brightest 

 where they were radial to the sun, and the black-centred bands 

 were equally marked when they were tangential to the limb. 



My observations were completely confirmed by those made by 

 Captain Branfill, of Major Tennant's expedition. 



Instead of being negative, I consider the results obtained by 

 the polariscope to have been conclusive as to the cause of the 

 corona of the eclipse of 1868. In order to give a reflecting angle 

 calculated to produce the amount of polarization observed, the 

 reflecting atmosphere must have surrounded the sun. 



Yours very truly, 



G. K. Winter. 



Phil. Mag. S. 4. Vol. 39. No. 258. Jan. 1870. C 



