HIStORY of the SOCIETY. 9 



This arch did not exceed 7 or 8° in length ; it was of the 

 fame breadth with the principal bow ; it had the colours in the 

 fame order, and nearly of the fame brightnefs ; or, if any differ- 

 •ence was difcernible, it was, that the tranfition from one co- 

 lour to another was not made with fo much delicacy in the laft- 

 mentioned rainbow as in the former. 



We recollected that a phenomenon fimilar to thi$ is defcri- 

 bed in the Philofophical Tranf actions, as having been £t^.Vi. at 

 Spithead, and that it is afcribed by the gentleman who obferved 

 it to the reflection of the fun's rays from the furface of the fea, 

 fo as to fall on the cloud where the rainbow was formed. This 

 hypothefis feemed to agree exactly with the phenomenon now 

 before us. 



The accidental rainbow, for fo it may be called, was feen 

 only at the extremity where the principal arch rofe from the 

 fea, and where," of confequence, the fun's rays, reflected from 

 the furface of the water, at that moment very fmooth, might 

 fall on the drops of rain. The other parts of the cloud could 

 not receive rays fo reflected, as the land intervened, and there, 

 accordingly, no veftige of the accidental rainbow was obfer- 

 ved. 



• 1 1 

 The accidental. rainbow lay, as was already faid, on. the fide 



toward the fun, and, this is agreeable to the hypothefis ; for the 

 rays that after reflection from the furface of the water fell on 

 the drops of rain, muft have come as from a point as much de- 

 prefled below .the horizon, as the fun was at that inftant eleva- 

 ted above it. The axis of the accidental rainbow muft there- 

 fore have made with the axis of the principal, an angle equal 

 to twice the fun's elevation, and its centre muft have been ele- 

 vated by that fame quantity above the centre of the other, fo 

 that if it had been complete, it would have been wholly between 

 the principal rainbow and the fun. 



B The 



