TRANSACTIONS OP THE SECTION'S. 33 



produced by rotation is assumed to be liglit so distributed in relation to space as 

 to produce blueness ; and when the intermittent light brings the black spaces to 

 apparent rest, they give back to the eye no part of the flash, but simply present this 

 diffused light of the zone. On the other hand, the white intervals between the 

 black spaces receive the flash and give it back, so that they reflect light in such re- 

 lation to area as is necessary for the presentation of orange. The black spaces being 

 circidar, the white intervals between them are wider at the outer and inner circum- 

 ference of the zone than in the centre ; and hence the diffused light varies in cha- 

 racter, and manifests itself in the negations as blue, light blue, and green ; and in 

 the intervals as dai'k orange, light orange, and yellow. 



Method of interpreting some of the Phenomena of Light. 

 By William Thomas Shaw. 



Tlie Cliromascope, and what it reveals. 

 By JoHK Smith, M.A., Perth Academy. 



The author said that he had described at the Meeting at Oxford certain experi- 

 ments exhibiting phenomena of colour, in order to elicit the opinion of philosophers 

 as to the cause of the colom's ; that the opinions then given, and those which he 

 has since met with have completely failed, m his opinion, to meet the difficulties of 

 the question. 



The experiments he considered demonstrated the true physical conditions of the 

 two colours red and blue. If we take the expression "pressure in time," from 

 Nevrton, to mean the time of action of a vibration of light, then the interval v^oll 

 mean the time of reaction. If two forces impinge on the eye at the same time, and 

 if the one be at its maximum and the other at its minimum phase, these two forces 

 will represent the two physical conditions of the red and the blue rays ; for during 

 a pulsation the one will be always keeping up its velocity, while the velocity of the 

 other will be constantly diminishing. This the author illustrated by many exam- 

 ples, which were explained by appropriate diagrams and drawings, sho^ving how 

 the two forces were generated. He was also of opinion that the exhibition of colour 

 was the only evidence by which we could deduce that two such forces were in exist- 

 ence, but when once deduced could be verified by reversing the experiment. 



Tlie Prism and Cliromascope. By John SMini, M.A., Perth Academy. 

 In this paper the author said, that having, as he considered, demonstrated in his 

 former paper, by experiments from the chromascope, the physical conditions of the 

 two extreme rays of the prism, he felt himself authorized to extend the discoveries 

 made by the chromascope to the illustration of the prism. That, by a legitimate 

 process of reasoning, he thought he was justified in concluding that the same law 

 was in operation in the chromascope and prism, although the processes were dif- 

 ferent. That this law explained, in the most simple manner possible, the cause of 

 the colour of thin plates of soap-bubbles and such other phenomena. That these 

 explanations all followed as logical inferences from the same law, without any 

 additional supposition or amendment. But that, in whatever light this theory 

 might be viewed, he considered that the experiments which he had described could 

 not be solved by any other theoiy, while they enabled him to give a very rational 

 explanation of the prism. 



On the Panoramic Lens. 

 By Thomas Sctton, B.A., Lecturer on Photography at King^s College, London. 



The lenses commonly iised by photographers for taking views have this gTave 

 defect,_ viz. they include too narrow a field of view for a large and important class 

 of subjects. The author has invented a lens which remedies this defect, and pro- 

 duces an optical image which includes an angular field of 100° and upwards in 

 perfect focus to the extreme ends of the picture. This lens, which is an entirely 

 new optical instrument, unlike anything else, ho has called a "Panoramic lens," 

 and will now describe. 



1861. 3 



