282 



of the day. In some cases, there is a perfect compensation, 

 the partially polarized light of the sky being restored to 

 common light by the reflection of the water. In other cases 

 the light of the sky has its polarization increased by re- 

 flexion from the water in the same plane in which it was 

 itself polarized ; and in other cases, the compensation is 

 effected only in particular planes. At sunset, for example, 

 the light reflected from the sea at a great obliquity in two 

 vertical planes inclined 45° to a vertical plane passing through 

 the sun and the observer, is compensated in these two planes, 

 or the plane of its polarization is inclined about 45° to the 

 reflecting surface. The same observations apply to the light 

 of the two rainbows when reflected from the surface of 

 water. 



" 6. When the light of the sky, or of the rainbow, is re- 

 flected from surfaces not horizontal, such as the roofs of 

 houses, sheets of falling water, or surfaces of smoke and va- 

 pour, the compensations are more varied, and a perfect 

 neutralization of the light by the second reflexion is more 

 frequently obtained." 



Professor Lloyd mentioned some circumstances which 

 appeared to be opposed to Sir David Brewster's views. 



Professor Kane commenced the reading of a paper " on 

 theTannin of Catechu, and the chemical Substances derived 

 from it." 



The abstract of this paper will be printed when the con- 

 clusion has been read. 



DONATIONS. 



Transactions of the Zoological Society of London. Vol. 

 III. Part 1. 1842. 



Reports of the Auditors atid Council of the Zoological 

 Society of London, A2iril29th, 1842, and List of Members. 



