564 REPORT— 1897. 



9. Increase of Segmental Vibrations iyi Aluminium Violins. 

 By Dr. A. Springer. 



Continued experiments made with aluminium sound boards have verified the 

 statements made by the author tive years ago, that aluminium possesses acoustical 

 properties more closely allied to those of wood than those of metals. Metals in 

 general give rise to comparatively continuous and uniform maintenance of higher 

 upper partial tones, frequently inharmonic to the prime, making the tone ex- 

 tremely penetrating and unmusical. In wood the mass is small, the natural 

 structure irregular, being full of countless interstices, the elasticity comparatively 

 imperfect causing the higher proper tones to rapidly die away. Aluminium not 

 only possesses the latter property, but to a much more marked degree; on 

 account of its lightness and probably intermolecular friction the higher upper 

 partials require special construction of a sound board to become audible. In wooden 

 instruments provision must be made to prevent the bass notes from entering into 

 segmental vibrations detrimental to upper partials, thereby giving a dull purity of 

 tone, lacking in brilliancy. To avoid this effect the author was obliged to depart 

 from the fixed rules adopted by violin makers and work in a manner diametrically 

 opposed to them. 



The author showed by means of open model an aluminium cross section under 

 the bridge instead of bass bar and a reinforcement of centre of the belly and back, 

 by which means the segmental vibrations are produced. 



After the paper was read a violinist played on one of the instruments exhibited, 

 illustrating the various points discussed. 



Department II. — Meteorology. 



1. Report on Observations at the Ben Nevis Observatory. 

 See Reports, p. 219. 



2. Mejoort on the Application of Photography to the Ehicidation of 

 3Ieteorological Phenomena. — See Reports, p. 128. 



3. Monthly and Annual Rainfall in the British Emjnre, 1877 to 1896. 

 By .John Hopkinson, F.R.Met.Soc, Assoc.Inst.C.E. 



Nearly twenty-four years ago there appeared in ' The Colonies ' a letter from 

 Mr, W. Sowerby suggesting that residents in the British Colonies should be 

 invited to contribute notes and queries on natural objects. This was followed by 

 a letter from Mr. G. J. Symons, F.R.S., adding a similar plea on behalf of 

 Meteorology. These suggestions met with the approval of the Editor of 'The 

 Colonies,' and he invited the Directors of the principal Colonial Observatories to 

 supply monthly reports of meteorological observations, and arranged with Mr. 

 Symons to supervise them. 



The first table published was for January 1874, and contained reports from 

 sixteen meteorological stations in the British Empire. The tables were continued 

 to June 1881, after which date they have appeared in Symons' 'Monthly 

 Meteorological Magazine.' In the table for .December 1896 are records from 

 eighteen stations, but only seven of these are survivals from January 1874. The 

 rainfall at ten of these stations can be carried back for at least twenty years, and 



