Cambridge Philosophical Society, 71 



by Mr. A. Smith, of Trinity College, was read, containing a simple 

 method of performing the eliminations by which we may obtain Fres- 

 nel's equation to the wave surface in biaxal crystals, according to the 

 undulatory theory of light. Mr. Whewell read a letter from Prof. 

 Schumacher in which it was stated that Messrs. Bier and Modler 

 have, by observations of two remarkable spots during several months, 

 fixed the time of Jupiter's revolution at 9 h 55 m 26£ s being a lon- 

 ger time by 5^ s. than that mentioned by Prof. Airy at the last meet- 

 ing, as the result of his observations. It was also stated that M. 

 Bessel had observed a long series of elongations of Jupiter's satellites, 

 and that these give the mass of Jupiter nearly identical with that ob- 

 tained by Prof. Airy. Mr. W. M. Fisher made further observations in 

 confirmation of the views explained in his former communication re- 

 specting Tubercles. 



Monday evening (June 18th), Dr. Clark, V.P. in the chair. Mr. 

 Willis gave an account, illustrated by models, of the progress of ar- 

 chitectural art in the vaulting of churches in the middle ages. He 

 observed that the Romans had devised arrangements by which paral- 

 lelograms of unequal sides could be covered with vaults, as, for in- 

 stance, in the baths of Diocletian. In this case we have parts cor- 

 responding to the side aisles, buttresses, and clerestory windows of 

 the churches of later times. But a great revolution took place in the 

 decorative construction of such vaults when, instead of resting on 

 their supports as a solid mass, the ribs alone were multiplied to re- 

 ceive the increased number of members of the vaulting and of the 

 pier arches, so as to form clustered piers. Differences were noticed 

 between the treatment of such piers in England and in other 

 countries. 



IX. Intelligence and Miscellaneous Articles, 



BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE I 

 MEETING AT DUBLIN IN AUGUST NEXT. 



rTIHE next Meeting of the British Association for the Ad- 

 JL vancement of Science will take place in Dublin, and will occupy 

 the week, commencing on Monday, August 10th. It is anticipated that 

 this meeting will present as many objects of interest to the friends 

 and cultivators of science, and will be as numerously attended as those 

 which have been held in previous years at Oxford, Cambridge, and 

 Edinburgh. 



The following is extracted from the circular addressed to the mem- 

 bers by Dr. Hamilton and the Rev. H. Lloyd, Secretaries for Dublin. 



" Dublin, July 1st, 1835. — It is requested that Members who may 

 have any papers, or other communications, to lay before the Associa- 

 tion, will state, before the end of July, their general nature and pro- 

 bable extent, in letters addressed as follows : 



To the Provisional Secretary of the [Mathematical or Chemi- 

 cal, or other] Section, Royal Irish Academy, Dublin. 

 Unless this precaution be attended to, great inconvenience must arise, 



