The Rev. Samuel Haugliton on the Granites of Scotland. 59 



vations, from 1837 to 1869 inclusive, of the four great earth-ther- 

 mometers sunk into the rock of the Calton Hill, at the Royal Ob- 

 servatory, Edinburgh, by the late Principal Forbes, pursuant to a 

 vote by the British Association for the Advancement of Science. 



Leaving on one side the several natural-philosophy data which 

 have been investigated from smaller portions of the same series of 

 observations 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 dif- 

 ferent 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 ob- 

 served may at once be turned, no matter to what cosmical origin 

 their existence may be owing. 



" On the Constituent Minerals of the Granites of Scotland, as 

 compared with those of Donegal." By the Rev. Samuel Haughton, 

 F.R.S., M.D. Diibl., D.C.L. Oxon. 



During the past summer (1869) I completed my investigation 

 of the constituent minerals of the Scotch Granites, and secured spe- 

 cimens, from the analysis of which I obtained the following results :— 



I. Orthoclase. 



No. 1. No. 2. No. 3. No. 4. 



Silica 65-40 64-44 64*48 64-48 



Alumina 19*04 18'64 20*00 20*00 



Peroxide of iron ... . trace. 0'80 none. none. 



Lime 0*22 0*66 1*01 078 



Magnesia trace. trace. trace. none. 



Soda 3*63 2*73 1*72 2-19 



Potash 11-26 12-15 12*81 12-10 



Water 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, x\berdeen. 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, 

 translucent, large crystals. 



