xxiv Proceedings. [April 2nd, igoi. 



Ordinary Meeting, April 2nd, 1901. 

 HoKACE Lamb, M.A., LL. D., F.R.S., President, in the Chair. 



The thanks of the members were voted to the donors of the 

 books upon the table. 



Mr. W. E. HoYLE exhibited an old form of dial, bearing the 

 name " Nathaniell Jeynes," and the date " 1678," which had on 

 one side a small circular rotating plate inscribed with the circum- 

 polar constellations. 



Mr. HoYLE also showed a silhouette portrait of Dr. Thomas 

 Percival, one of the founders of the Society. 



Mr. C. E. Stromeyer mentioned that on several occasions 

 he had seen the sun's rays converging to a point directly opposite 

 to the sun. In one case, when the sun was very low on the 

 western horizon, some very marked rays, caused by a low bank 

 of clouds, converged towards a point above the eastern horizon. 



Mr. J. J. AsHWORTH (Treasurer) having taken the Chair, 



The President communicated some numerical illustrations 

 of the Diffraction of Sound. These were intended to show the 

 extreme facility with which sounds of relatively large wave-length 

 can make their way round obstacles or through apertures. Thus, 

 with a wave-length of 4 feet, a wire -^is of an inch in diameter 

 dissipates only the fraction 6"6 x lo"** of the energy which falls 

 upon it ; a spherule of water t^tV^ °^ ^" ^"'^^'^ ^" diameter scatters 

 only i"3xio~"'. Again, a perforated screen or grating may 

 present hardly any obstacle to the transmission of sound, 

 although the apertures occupy only a small proportion of the 

 total area. Reference was made to the bearing of such results 

 on the attempts made to improve the acoustic properties of 

 buildings by hanging wires, and on current notions as to the 

 possibility of the reflection of sound from clouds. 



A discussion ensued, in which Messrs. Barnes, Lees, 

 Stromeyer, and others participated. 



