1907-1908-] NebulcB and Nebular HypotJieses. 67 



shire, &c., chiefly, it seems, in the west. I am unaware of its 

 having been found so far east as Edinburgh before. 



2. Pallavicinia Flotowiana (Nees), Lindb. — This is a very 

 rare hepatic, of which I found a little last year, mixed with 

 mosses, in a marsh on Gullane Links, but this year I gathered 

 it in another place on the same links in great abundance and 

 in fine condition. It grows on damp spots among seaside sand 

 dunes, on ground apt to be covered with water in winter. In 

 Scotland it has hitherto been found only on the Sands of 

 Barrie, Forfarshire, and on Tents Muir, in Fife. In England 

 and Ireland it has been gathered in a few similar places, such 

 as Coatham marshes, at the mouth of the river Tees, and on 

 Southport sands, Lancashire. 



IX.—NEBULJE AND NEBULAR HYPOTHESES. 



By Mr G. CLAEK, M.A., Kotal Observatory, Edinburgh. 



{Communicated, Oct. 28, 1908.) 



I SHOULD like to remark by way of introduction, that we may 

 draw several reasonable inferences regarding the stars merely 

 from common-sense principles, and without any appeal to 

 accurate scientific knowledge. For example, in our terrestrial 

 experience luminosity is always a temporary phase of existence. 

 A fire burns only so long as its fuel will last : the electric light 

 depends upon the constant charging of the storage batteries : 

 a, bar of red-hot iron soon loses first its light and then its 

 heat when it is removed from the furnace. Every form of 

 light with which we are conversant sooner or later fails and 

 is extinguished. 



To judge, then, by this experience, we should conclude that 

 the stars which we now see to be luminous cannot have been 

 so from everlasting, any more than they can be so to ever- 

 lasting. Reason and revelation alike assure us that a time 

 was when they were not, and that at some future epoch they 

 shall again have ceased to be. 



