Proceedings of the Royal Institution of Great Britain. 



FRIDAY EVENING MEETINGS, 1831. (CONTINUED.) 



April \bth. Mr. J. F.Daniell on the Forms and Attractions of the 

 Particles of Crystals. The subject of this evening forms the matter 

 of the paper at page 30 of the present Number of this Journal. 



The recent experiments made in Edinburgh by Mr. A. Trevellyan, 

 on the production of musical sound during the transference of heat, 

 by conduction, from hot pieces of metal to cold masses of lead, were 

 repeated before the members, with apparatus brought from Edin- 

 burgh, by Mr. Addams. 



April 22d. Mr. Marshall on the Origin and Utility of Cow-pox; 

 with the Causes of Failure in the practice of Vaccination. Mr. 

 Marshall introduced the subject by a short account of Dr. Jenner 

 and his exertions. He then proceeded to notice the effects of the 

 practice of vaccination, and the causes of its occasional failure. 

 From tables it appeared that the annual mortality in cases of small- 

 pox was reduced in Copenhagen from 450 to 9 ; in Prussia the 

 average was as 12 to 1 ; Berlin, in 1819, only 25 had died, being' 

 about 1 in 8000 ; Bavaria, in 11 years, only 5 had died ; Anspach, 

 the disease had been completely exterminated ; Norwich, in one 

 year the small-pox cutoff more persons than any disease, except the 

 plague ; Edinburgh, similar havoc ; London, in one year 13,000 

 died; Russia, from 1804 to 1812 there were upwards of 1,200,000 

 individuals vaccinated. 



Mr. Marshall then stated the various causes of failure, as age of 

 virus, want of care, bad selection, &c. &c. ; and the precautions 

 under which vaccination might be considered as a thorough barrier 

 to the small-pox. 



April 29th. Mr. Faraday on Mr. Trevellyan's recent Experi- 

 ments on the Production of Sound during the Conduction of Heat. 



Mr. Trevellyan had remarked that when a heated poker was laid 

 upon a table, so that the knob rested upon the table, but the 

 hot part upon an interposed block of cold lead, regular musical 

 notes were frequently produced. By extending his experiments, 

 he found that a better form than that of a poker might be used 

 for the hot metal : a piece of brass about four inches long, one 

 inch and a quarter broad, and half an inch thick, should have a 

 groove of one-eighth of an inch in width, formed down the middle 

 of one of the broad faces, and then that face bevelled from the edges 



