of Edinburgh, Session 1870-71. 
455 
Lastly, the spiral — , series 
A A 
1 2 3_ 5 _ 
4’ 9 ’ 13’ 22’ 
&c., which Dr 
Dickson formerly noted as occurring in a cone of Finns Pinaster , in 
the Museum, Edinburgh Botanic Garden, may readily he derived, 
as MM. Bravais have suggested,* from a spiral of the series 
1 1 2 
4’ 5’ 9’ 
_3 _5 
14’ 23 
, &c., thus, 
Table G -. — Showing possible derivation of a — Spiral from the System 
A A 
&c. 
D 
S 
D 
S 
D 
V 
— 
1 
4 
9 
13 
22 - 
5 
22 
1 
4 
5 
9 
14 
23 = 
5 
23 
The following Gentleman was admitted a Fellow of the 
Society : — 
Rev. Professor Crawford. 
Monday , 1 5th May 1871. 
Professor CHRXSTISON, President, in the Chair. 
At the request of the Council, Professor Tait gave an 
Address on Spectrum Analysis. 
(The following is a brief Abstract, consisting mainly of the Lecture 
Notes') : — 
I should not have thought of appearing before you to-night to 
lecture on so hackneyed a subject, had I not been assured by 
several members of the Council that such an address was really 
desired by many Fellows of the Society. It is a subject to which 
I have not paid very special attention, partly because it is in so 
many and such good hands, and partly because (except from the 
point of view of theory) it requires for its extension, especially to 
* L. c. p. 103. 
