892 Transactions. — Astronomy. 



also, I supposed was from the unsteadiness of the air ; but to 

 me it seemed certainly not the least striking part of the great 

 spectacle to see the sun flickering, as it were, before it went 

 down." 



Dr. J. Hudson says on this subject: " About five minutes 

 before totality I was standing with my back to the sun, looking 

 on the ground in front of me, when I saw fine films floating over 

 the surface of the ground. I rubbed my eyes, thinking there 

 must be water in them, and looked again ; there were the films 

 plainer than before. Soon they began to take more definite 

 shape, and appeared as long bands of light and shade, moving 

 rapidly across the field of vision from E.S.E. to W.N.W. I 

 thought for a moment, were they the shadows of clouds of mist ? 

 I looked up, but the whole atmosphere was perfectly clear, 

 besides there was no wind ; I held up my hand to feel, and it 

 was then what I should call a dead calm. However, there were 

 the long lines of light and shadow travelling rapidly in a westerly 

 direction, and more and more distinct did they appear until the 

 moment of totality, when they completely disappeared, to re- 

 appear again when totality was over. I cannot say what direc- 

 tion they travelled in after totality." 



Mr. A. Coleman, in his " Observations on the Solar Eclipse," 

 says : — 



" The phenomenon which most struck me, and to which I 

 believe I paid the most attention, was the peculiar vibratory 

 shadows which passed across the earth's surface during the 

 eclipse. Scientific observers have no doubt recorded and fully 

 accounted for this striking phenomenon, but never having read 

 of such, nor having seen any explanation for them, I venture to 

 offer one, which, however, may neither be original nor correct. 

 A curious property of light, discovered by Grirnaldi in 1665, 

 later on independently by Newton, but more thoroughly inves- 

 tigated by Fremel, was that termed the inflection or diffraction 

 of light. When a divergent ray of light admitted into an 

 apartment was just intercepted by an opaque spherical body of 

 a suitable size and at a suitable distance, surrounding the 

 shadow cast upon a screen were seen concentric rays of coloured 

 light, ' the fringes ' of Grirnaldi, whilst in the shadow itself 

 were to be seen alternate light and dark bands of light. 



" In investigating this latter phenomenon, Dr. Young saw 

 that they were capable of a satisfactory explanation upon his 

 admirable and comprehensive undulatory theory. To use his 

 own words, ' the fringes within the shadow were produced by the 

 interference of the rays bent into the shadow by one side of the 

 body (intercepting) by the rays bent into the shadow by the 

 other side.' 



" In the present instance the moon's disc formed the 

 obstructing body, causing the light and dark bands in its 



