4-62 Cambridge Philosophical Society. 



scribed three species of the pitcher plant ; and then taking a view of 

 the metamorphoses of certain parts of plants, endeavoured to show 

 what the pitchers really were, and what were their probable uses. 



May 13. Mr. Brockedon on the passage of the Alps by Hannibal. 

 Mr. Brockedon, from his extensive personal knowledge of the Alps, 

 was enabled to review the accounts given of this passage, and to 

 draw conclusions as to the true locality of the passage, which he 

 believes took place over the little St. Gothard. 



May 20. Mr. Robertson on a new practice of Painting, which 

 unites the force of other modes with extreme durability. Mr. Ro- 

 bertson's paintings are in water-colours, and upon paper. He uses 

 isinglass dissolved in hot spirit of wine between and over his colours, 

 by which they acquire the brilliancy and force of oil ; and when the 

 picture is finished, he covers it with a colourless copal varnish. The 

 pictures when large are lined with canvass and tin-foil. The dura- 

 bility and steadfastness of the colours appear to be extreme. 



CAMBRIDGE PHILOSOPHICAL SOCIETY. 



A meeting of the Philosophical Society was held on Monday 

 evening, May the 9th, Dr. F. Thackeray, the Treasurer, in the chair. 



There were presented to the Society a specimen of the Squacco 

 Heron, by Mr. Price of St. John's College, and a very fine Coral- 

 line, from Madeira, by Mr. Lowe of St. John's College. A paper 

 by Mr. Pritchard of St. John's College was read, " On a method 

 of simplifying the investigation of the figure of the earth considered 

 as heterogeneous." The remainder of a paper by Professor Whewell 

 was also read, " On the mathematical exposition of the leading 

 doctrines in Mr. Ricardo's Principles of Political CEconomy and 

 Taxation." It was shown that Mr. Ricardo's proposition, that a 

 tax upon wages must necessarily fall upon profits, cannot be main- 

 tained on his own principles. When stated mathematically, the 

 question leads to an indeterminate problem, in which the rise of 

 price and the fall of profits mutually depend on each other, and 

 neither can be determined without some further assumption. Si- 

 milar modes of investigation were then applied to the doctrine of 

 exports and imports, and the different value of the money-metals in 

 different countries, in consequence of their influx and efflux pro- 

 duced by manufacturing skill and other causes. Finally, formulae 

 were given on which, according to such principles, the rate of ex- 

 change will depend. Mr. Whewell concluded by observing that he 

 did not put forward such formulae as applicable to practice, but as 

 exhibiting the results of Mr. Ricardo's theories : and that if the 

 principles were true and certain, mathematics would be the proper 

 instrument for obtaining their consequences. 



After the meeting Mr. Willis exhibited a numerous and curious 

 series of experiments upon the subject of sound. Among these 

 were, first, the experiment (originally made by Hooke) of the pro- 

 duction of the definite musical sound by the impulses of the teeth 

 of a revolving wheel upon a card ; by means of which contrivance 



the 



