Cambridge Philosophical Society. 4-63 



corners in rainy weather, declaring war against everything in the 

 shape of a fly or musquitoe. 



The Paper was also accompanied by drawings of the egg, larva, 

 and pupa of Urania Fernandince, which were exhibited. 



CAMBRIDfiE PHILOSOPHICAL SOCIETY. 



A meeting of the Cambridge Philosophical Society was held on 

 Monday evening, April the 14th, Professor Airy, V.P., in the chair. 



Various presents were received, among which were the memoirs 

 and other publications of the Royal Academy of Sciences at Brussels. 

 Professor Airy read a communication containing an account of his 

 determination of the latitude of the Observatory of Cambridge, by 

 means of observations with the mural circle. The latitude thus de- 

 termined appears to be 52° 12' ol "72, which Professor Airy consi- 

 ders to be accurate within a small fraction of a second. 



Mr Whewell maJe some remarks on the subject of Sir John Her- 

 schel's hypothesis respecting the absorption of coloured media, pro- 

 posed in the Philosophical Magazine for December 1833. The ob- 

 ject of these remarks was to show that the theory might be simpli- 

 fied ; and it was further added, as suggested by Mr. D. Heath, that 

 the same hypothesis would lead to an explanation of dispersion by 

 refraction on the undulatory theory. These statements led to com- 

 munications and remarks from several other members. 



A meeting was held on Monday evening, April 28th, Dr. Clark, 

 V.P., being in the chair. 



A paper by Professor Miller was read on the subject of a supposed 

 relation between the axes of optical elasticity of oblique prismatic 

 crystals, and the axes of their crystalline forms. Professor Neumann 

 of Koningsberg, had asserted, on the strength of observations made 

 on certain species of crystals, that the crystalline forms might be re- 

 ferred to the optical axes in a manner consistent with the simplicity 

 of crystalline relations; but in the instance of several other species 

 examined by Professor Miller, it appeared that this law could not be 

 maintained. 



A paper by Mr. Earnshaw, of St. John's College, was also read, on 

 the laws of motion. Mr. E. is of opinion that the three laws of motion 

 are not proved by experience, but by means of the axiom, that similar 

 effects are due to similar causes. Having established, by help of this 

 principle, the laws which connect motion and force, we learn from 

 experience in what cases force exists. 



Mr. Willis exhibited and explained the construction and working 

 of a machine which be had invented for the purpose of jointing toge- 

 ther the bones of skeletons, the object being to connect the bones so 

 that they may exhibit, in some degree, their natural motions. Mr. 

 Willis's machine holds the bones firmly, however irregular their form ; 

 saws notches in their extremities, so that they may be jointed by 

 means of a metal plate; and drills the holes bv which the plate is 

 fastened. 



A meeting was held on Monday evening, May the 12th, Dr. F. 

 Thackeray, the Treasurer, being in the chair. 



