PROCEEDINGS OF SOCIETIES. 87 



Dadylopora, he (the President) put into his hands a very large collec- 

 tion of shells collected by Sir Charles Lyell, and he (Dr. C.) found 

 still more wonderful forms of this type, supj)osed to be coral. The 

 whole thing showed how the recent is connected with the fossil, 

 when genus after genus, and species after species are put together 

 into one category, and shown to be essentially one specific type. Dr. 

 Carpenter, by his great skill in Dadylopora alone, had produced one 

 of the most beautiful monograjshs in existence, an exact counterpart of 

 the same thoughtful work in which Mr. Carruthers was engaged. 



Dr. Eoyston-Pigott, referring to the paper of Dr. Anthony, pub- 

 lished in the current number of the Journal, said, if an object be 

 carefully illuminated by a central light, not overflooding it, so that 

 all milkiness may be avoided, and if the observer took the trouble to 

 insert different apertures of the diaphragms behind the object-glass, 

 some very curious effects would be seen, and the remarkable pheno- 

 mena obtained by this arrangement were worthy of notice. Dr. An- 

 thony's paper had put him in mind of what he himself had seen in 

 the battledore scale. He (Dr. Pigott) had noticed that if you have 

 a very good -|th, no new features would be displayed, and only 

 the usual rows of beads would be seen ; but when the apertiu'e is 

 gradually reduced, it becomes a very remarkable object ; for you will 

 not only see the large beads, but thousands of others, which stand up 

 with remarkable precision, so much so that you can see them shaded 

 black, and the whole scale usually only marked with parallel ribs 

 studded all over with beautiful beaded effects. He wished to call the 

 attention of the Society to the fact that, by reducing aperture, you 

 may get some very singular revelations. If there were any photo- 

 graphers i^resent that evening he would appeal to them to confirm the 

 principle laid down by Sir David Brewster, who has said that you cannot 

 get a true picture if you use a very large camera upon a small object. 

 Dr. Pigott then described the distortions which would occur in a 

 portrait where too large a camera was used, and which, according to 

 Sir David's principle, were caused by the mixing up together of all 

 the images caused by different areas of the camera lenses ; so that 

 the result of such a proceeding would be that a compound image 

 would be obtained, but not a likeness. To show the portrait correctly, 

 you must diminish the glasses, as nearly as you can, to the aperture 

 of the eyes ; and you then photograph the object nearly by parallel 

 rays. 



Dr. Pigott then illustrated the principle for which he contended 

 by a description of the effects that would be produced by a number 

 of cameras, all photographing one and the same head, at the same 

 instant. The right ear would be shown by one, the left by another, 

 and so forth. In the same way, if the object-glass be of very large 

 aperture a great many views of the same elevated object under the 

 microscope are all different, yet all these views are mixed up into 

 one compound image. The eye of the observer was receiving rays 

 from every side of a minute object at once, as well as from the top. 

 He was looking at it from innumerable points of view at one and the 

 same instant. But when the aperture was reduced, immediately the 



