264 



but the principal difference observable is at the pylorus, because, as 

 Mr. Home conceives, some animal substances, after solution, are less 

 readily changed into chyle than others. 



In the most perfectly carnivorous animals, the internal membrane 

 is extremely uniform in its appearance ; but even in these a division 

 or capability of it by muscular contraction is observable. 



The first instance in which Mr. Home remarked this division in 

 the human stomach, was in a woman who was burnt to death, after 

 having been unable to take much nourishment for several days before. 

 But since that time, as he has taken frequent opportunities of ex- 

 amining the human stomach recently after death, he finds that this 

 contraction may generally be met with in a greater or less degree ; 

 but when a body is examined as much as twenty-four hours after 

 death, this appearance is rarely to be met with ; which accounts for 

 its not having been before particularly noticed. 



The series of stomachs arranged according to their structure, which 

 has been given, includes the principal peculiarities that appear to 

 Mr. Home capable of influencing the process of digestion : it is, 

 however, considered only as a first imperfect attempt, which he hopes 

 that other inquirers will render more complete. 



Experiments for investigating the Cause of the coloured concentric 

 Rings, discovered by Sir Isaac Newton, between two Object-glasses 

 laid upon one another. By William Herschel, LL.D. F.R.S. Read 

 February 5, 1807. [Phil. Trans'. 1 807, p. 180.] 



The account, given by Sir Isaac Newton, of these coloured arcs, 

 appeared to Dr. Herschel highly interesting, but he was not satisfied 

 with the explanation of them. Sir Isaac Newton accounts for the 

 production of the rings, by ascribing to the rays of light certain fits 

 of easy transmission and alternate reflection ; but this hypothesis 

 seemed not easily to be reconciled with the minuteness and extreme 

 velocity of the particles of light. 



With the view of inquiring further into the cause of these pheno- 

 mena, Dr. Herschel, so long since as the year 1792, borrowed of this 

 Society the two object-glasses of Huygens, one of 122, and the other 

 of 170 feet focal length. Notwithstanding various interruptions, the 

 series of experiments, made in the course of this time, has been car- 

 ried to a considerable extent ; and Dr. Herschel thinks the conclu- 

 sions that may be drawn from them, sufficiently well supported to 

 point out several modifications of light that have been totally over- 

 looked, and others that have not been properly discriminated. 



The aim of the present paper is to arrange the various modifica- 

 tions of light in a clear and perspicuous order ; but Dr. Herschel re- 

 serves his sentiments upon the cause of the formation of concentric 

 rings, for a subsequent communication. 



The first section describes different methods of making one set of 

 concentric rings visible. The first method consisted in placing a 

 double convex lens, of 26 inches- focus, upon a piece of glass, of which 



