Minutes of Proceedings. 
xxix 
Exhibition : The Chairman announced that the allotment of the grants 
in aid of research shall take place on the 27th inst. 
The Vice-President exhibited a photograph of the North Wall of the 
Cave at Heerenlogement, Cape Colony. The photograph shows the name 
of "F. Vailant," which was presumably inscribed by the traveller in the 
course of his journey in Namaqualand in 1783. The inscription was seen 
and described by Sir J. E. Alexander in 1836. The Cave is situated in the 
sand belt, about 40 miles S.E. from the mouth of the Oliphant's Eiver. 
The wall also bears the name of K. Zeyher, with the date 1829. 
Communications : — 
''The Spectrum of Euby," Part III., by J. Moik. 
Two further very faint spectrum-lines are described. The artificial 
ruby has been analysed, and chromium detected as the colouring matter. 
When a ruby is heated above 300° C, it changes, through scarlet and 
brown, to the colour of chromium glass, and all the characteristic 
spectrum lines disappear. It recovers completely on cooling. The effect 
of heat on the birefringence of corundum has been studied, and has 
been found to be insignificant. The spectrum of ruby is therefore due 
to chromium in a special atomic condition, which does not apparently 
occur elsewhere in Nature. 
" Some Causes and Effects of Variation in the Range of Temperature," 
by Dr. and Mrs. J. R. Sutton. 
This paper contains the results of a discussion of some of the more 
salient meteorological aspects of a variation in the range of temperature. 
It deals in a general way with the changes of temperature, moisture, 
pressure, and sunshine, which go with a variation in the range of tem- 
perature, monthly means being used. Harmonic constants of barometric 
pressure and temperature are computed for months of great and small 
range of temperature respectively. 
" Algebraical Development of the Elliptic Perturbative Function used 
in the Theories of Planetary Motion," by R. T. A. Innes. 
The paper presents tables whereby the functions, which operate on 
the ratio of the semi-axes, can be easily calculated to any order of the 
eccentricities and mutual inclination so far as regards primary and 
secondary terms which alone have any importance in the planetary 
theories. The paper concludes with an explicit development of the 
secular part of the perturbative function to any order. 
"A supposed new Mineral from Du Toitspan, Kimberley," by 
B. DE St. J. VAN DEE RiET. The supposed new mineral from Du Toitspan, 
Kimberley, reported in Nature (September 7th) by Mr. J. R. Sutton, 
appears to the author to be derived from a well-known artificial material, 
viz. : commercial calcium carbide. It is certain that acetylene generators 
have been in use on the mine for years, and it is quite possible that a 
