682 
Proceedings of the Royal Society 
fact, a solution, containing four arbitrary constants, given (with 
some misprints) in the “Memoir on Matrices,” and which (for 
convenience changing the signs) is as follows : — 
— a 
(P + yf 
(P + yf 
a + ft + y 
a + 13 + y 
a + ft + y 
(y + °0 X 
- P 
(* + »)£ 
a + P + y 
a + ft + y 
a + ft + y 
(«+ 0' 
( a + 
r 
“ 7 
a + ft + y 
a + ft + y 
a + ft + y 
(or, what is the same thing, we may omit the denominators, 
assuming a + /3 + y=l); it is, in fact, easy to verify that this has 
for its square the matrix unity. Moreover, we have, as above, 
p = - 1, q S- 1, r=l. 
2. Second Note on the Strain Function. By Prof. Tait. 
3. Note on the Rate of Cooling at High Temperatures. By 
Professor Tait. 
4. Notice of a Large Boulder in the Parish of Rattray, and 
County of Perth, having on one of its sides Cups and 
Grooves, apparently artificial. By D. Milne Home. 
About a year ago, the Council of this Society appointed a Com- 
mittee to make inquiry about boulders in Scotland. 
The Committee intend to submit to the Council a general report 
of their proceedings, showing the progress made. 
The object of the present notice is to give to the Society an 
account of one of the boulders reported to the Committee, as a 
specimen of the information which they have been obtaining. 
The Rev. Mr Herdman, minister of Rattray, in Perthshire, sent 
to the Committee an answer to their circular, specifying the follow- 
ing boulders and standing stones in his parish : — 
