22 



REPORT 1859. 



Logarithms. 

 C 1/9794999 

 D 1-9325036 

 E 1-8834154 

 F J/8477024 

 G 17947653 

 H j."7563732 

 Mean waveM 1-9701116 



Numbers. 

 0-9538934 

 0-8560588 

 0-7645667 

 0-7042103 

 0-6233979 

 0-5706545 

 0-9334940 



It is next pointed out that the Newtonian wave-lengths corresponding to the 

 lines of junction of the colours, are not reconcilable with the wave-lengths corre- 

 sponding to the fixed lines of Fraunhofer, and that this discrepancy arises from the 

 former having been deduced from an impure spectrum. It is shown, however, that 

 if the primary series on which Newton's numbers are based be assumed without 

 subjecting it to the process of taking the cube roots of the squares, and if it be mul- 

 tiplied by the mean wave-length in decimal parts of a French inch, it will present a 

 series agreeing better with Fraunhofer's wave-lengths. The result is exhibited in 

 the following Table, omitting the prefixed ciphers : — 



13554 



This series makes the interval between the extreme violet and the extreme red as 

 1 to 2, corresponding to the musical octave. 



It is in conclusion suggested that fresh observations should be made, under the 

 sanction of the British Association, on the wave-lengths corresponding to the bor- 

 ders of the coloured spaces in the diffracted spectrum, to ascertain if they be accu- 

 rately represented by the above series ; so that the existing error, in regard to the 

 estimated values of those wave-lengths, may no longer be perpetuated. 



On the Production of Colour and the Theory of Light. 

 By John Smith, M.A., of Perth Academy, Perth. 



The author had come to the belief, by means of experiments, that colour is pro- 

 duced by alternate light and shade in various proportions. To prove this, he caused 

 a white ray to revolve at various speeds on a black surface. His first experiment was 

 to move a slip of white card-board over a black surface. By this motion he obtained 

 a distinct blue ; afterwards, in different weather, the same thing produced a purple. 

 He then made a disc with five concentric rings. One ring was painted one-third 

 black, the rest of the ring being white ; the next ring was two-thirds black and one- 

 third white ; the next was three-fourths black and one-fourth white, and the fifth 

 half black and half white. This disc, when made to revolve, became completely 

 coloured ; there were no more blacks or whites visible, but five rings of different 

 colours. On a bright day with white clouds in the sky, the 



1st ring was of a light green : much yellow. 



2nd ring purple : very blue. 



3rd ring nearly as first. 



