172 



It is right that I should make this announcement without further 

 delay, as the fact now mentioned necessitates some revision of my 

 view respecting the nature of the impregnating influence, as expressed 

 in the paper alluded to. This I propose to make, and to lay very 

 soon before the Royal Society. 



I remain, my dear Sir, 



Yours very faithfully, 

 Thos. Belly Esq., Sec. R.S. George Newport. 



2. ''Further Experiments on Light." By Heniy Lord Brougham, 

 F.ILS., Member of the Institute of France, and of the Royal Aca- 

 demy of Sciences of Naples. Received I\Iarch o, 1852. 



1 he author commences this account of his experiments by remark- 

 ing, that " it is probable that some may consider the inference to be 

 drawn from the folio '.ving experiments as unfavourable to the doc- 

 trines of my former paper — I think I can explain the phenomena 

 according to those doctrines — but be they ever so repugnant, we are 

 of course in search of truth, and have no right even to wish that the 

 balance may incline one way rather than another, far less to conceal 

 any facts which may affect its inclination." 



The leading experiment is this : — A speculum is placed in a beam 

 of light and is inclined so that the reflected rays shall make a small 

 angle with the surfaces. Near the speculum the axis of reflected 

 rays coincides with that of the direct rays, but at a greater distance 

 the two discs are separate. The speculum being placed horizontally 

 across the pencil, coloured fringes appear both on the upper and lower 

 side of the reflected disc. These two sets of fringes are alike in their 

 colours and in the order of their colours, but the upper fringes are 

 narrower than the lower, and they diminish in breadth with their 

 distance from the disc, while the lower ones increase in breadth with 

 their distance. If only one edge of the speculum is in the 2:jencil 

 there are cnhr fringes on one side of the disc. 



It appears that the breadth of the fi'inges is in some inverse pro- 

 portion to the breadth of the speculum. When the sj)eculum is a 

 triangle with a very acute angle, the broadest fringes, and those most 

 removed from the disc, ansvrer to the points of the speculum where 

 it is narrowest, and they increase regularly towards the point which 

 answers to the acute angle or apex of the speculum. Their form is 

 hyperbolic. 



When the edges of the speculum are pai-allel, the disc near to it 

 is filled with groups of fringes which vary in num.ber, in breadth and 

 in colour, at all the distances from the speculum. At one distance 

 they form only a dark line running through the disc, and this is deep 

 purple when examined closely. At a greater distance the fringes 

 have other colours, and become broader again ; and at a still greater 

 distance the}' emerge into the shadow on both sides of the disc. 



The phenomena cf reflexion, it is stated, closely resemble those of 

 flexion, as to the fringes, their colours, their magnitude, their varia- 

 tion at different distances from the bending edges, and at difl'erent 

 distances of those edges from each other. 



