GO Report on the Solar Eclipse Expedition to Pulgaon. 



with unexpected vividness. They were seen at all points within 30 

 of the sun, with little or no variation in vividness, and as the instru- 

 ment happened first to be held, the bands were approximately 

 parallel to the sun's axis. These vivid bands are attributed to the 

 polarisation of the light scattered (diffracted) by solid particles in 

 the earth's atmosphere. 



The bands were so disconcertingly vivid that a few moments were 

 wasted in inspection of the instrument, but immediately afterwards 

 observations were quietly renewed, the search for faint coronal exten- 

 sions was abandoned, and attention was confined to the phenomena of 

 polarisation. 



The instrument was rotated about its axis, and the bands faded 

 from view and became invisible in a certain position. It was thought 

 immediately after the eclipse that the observations made were enough 

 to prove that the plane of polarisation was neither vertical nor hori- 

 zontal, but it has since been found that the evidence is not such as to 

 warrant this statement. When the bands had become invisible in 

 the outer part of the field of view, the rotation of the instrument was 

 discontinued for a moment. The eye then gradually became aware 

 of faint colours over the corona, but the distribution appeared to be 

 uneven rather in patches than in bands. These colours are attri- 

 buted to the polarisation proper of the corona. The " patchy " dis- 

 tribution is doubtless a result of the nature (presumably radial) of 

 the polarisation of the corona, and of the largeness of the scale of 

 the bands compared with the diameter of the moon (1 25' : 33'). 

 The fact that the colours appeared faint in contrast with the vivid 

 sky-bands previously seen may be referred to several alternative 

 explanations which cannot well be dealt with here in detail. It is 

 obvious that the ratio of the brightness of the light scattered by 

 the sky to that of the light of the corona plays as important a part 

 as the proportion of the coronal light that may be regarded as 

 polarised. 



Next, attention was directed to the corona near the limb, and the 

 central part of the central band was observed while the instrument 

 was rotated, the central band being kept radial to the sun's disc. 

 The observed central part was seen to be bright at all points round 

 the limb on the east side, whether the central sky-band were bright 

 or dark. 



Then the bands were set so that one of the first dark lateral bands 

 was tolerably close to the moon's limb, with its centre perhaps half a 

 moon's diameter from the limb. The band was observed to be bright 

 near the limb, and to be dark at a short distance on either side. 



Both of the last mentioned observations point to the idea that the 

 light scattered by the atmosphere was comparable in brightness with 

 the corona at points not far distant from the sun's limb. 



