312 Rev. Samuel Haughton on the Granites of Scotland. [Apr. 7, 



both by Principal Forbes and Sir William Thomson, the author applies 

 himself solely to trace the existence of other cycles than the ordinary 

 annual one, in the rise and fall of the different thermometers. 



Of such cycles, and of more than one year's duration, he considers that 

 he has discovered three ; and of these the most marked has a period of 

 1 1 • 1 years, or practically the same as Schwabe's numbers for new groups 

 of solar spots. Several numerical circumstances, however, which the 

 author details, show that the sun-spots cannot be the actual cause of the 

 observed waves of terrestrial temperature, and he suggests what may be, 

 concluding with two examples of the practical use to which a knowledge of 

 the temperature cycles as observed may at once be turned, no matter to 

 what cosmical origin their existence may be owing. 



II. u On the Constituent Minerals of the Granites of Scotland, as 

 compared with those of Donegal."" By the Rev. Samuel Haugh- 

 ton, F.R.S., M.D. Dubl., D.C.L. Oxon., Fellow of Trinity Col- 

 lege, Dublin. Received March 31, 1870. 



During the past summer (1869) I completed my investigation of the 

 constituent minerals of the Scotch Granites, and secured specimens, from 

 the analysis of which I obtained the following results : — 





I. Ortkoclase. 









No. 1. 



No. 2. 



No. 3. 



No. 4. 





. . 65-40 



64-44 



64-48 



64-48 





19*04 



18-64 



20-00 



20-00 



Peroxide of iron . . 



. . trace. 



0-80 



none. 



none. 





0-22 



0-66 



1-01 



0-78 







trace. 



trace. 



none. 



Soda 



. 3-63 



2-73 



1-72 



2-19 



Potash 



, 11-26 



12-15 



12-81 



12-10 





. 0-20 



0-80 



0-64 



0-08 





99-75 



100-22 



100-66 



99-63 



No. 1 . Stirling Hill, Peterhead. Occurs in an eruptive Granite, in veins, 

 in well-developed reddish-pink opaque crystals, encrusted with crystals of 

 Albite. 



No. 2. Rubislaw, Aberdeen. Large beautiful reddish-pink opaque crystals 

 in veins, associated with white Mica. The Granite of Rubislaw is of 

 metamorphic origin, and different in character from the eruptive Granite 

 of Peterhead. No Albite has been found in it. 



No. 3. Peterculter, Aberdeen. In metamorphic Granite ; white, trans- 

 lucent, large crystals. 



