Intelligence and Miscellaneous Articles. 403 



siderable progress since they were reported upon by Mr. Mitford 

 last year *. There are four scams of coal, each about 7 feet thick, 

 from 50 to 100 feet apart. A tunnel has been driven through one 

 of the seams for a distance of between 150 and 250 feet, and at an 

 elevation of 430 feet above the sea. Prom this the coal obtained is 

 carried down to the shore on the backs of men, mules, and ponies. 

 The writer adds that there is abundance of coal " of the canrel 

 description." 



2. "On a peculiarity of the Brendon-Hills Spathose Ore-veins." 

 By M. Morgans, Esq. 



The author described the Brendon Hills as consisting of a Devo- 

 nian slate dipping S. by E. and N. by "W. on the two sides of the 

 axis of elevation. The cleavage -laminae dip S. by W. at an angle 

 of 80° ; and the cleavage-strike forms only a slight angle with that 

 of the beds, which, however, is sometimes irregular. Veins of 

 spathose iron-ore, very rich in manganese, occur in the slate ; and 

 the general dip of these appears to coincide with that of the cleavage- 

 planes. The veins consist of thin " tracks" of softened clay-slate 

 and quartz, with larger or smaller pockets of productive ore. These 

 metalliferous portions do not descend parallel to the line of their 

 dip, but slope more or less, usually to the west. The author stated 

 that the veins have been segregated from the adjoining clay-slate, 

 the unproductive portions of them occurring where the conterminous 

 strata were not impregnated with sufficient ferruginous matter to 

 produce a lode of iron-ore ; the slope of each productive part, called 

 " eud-slant " by the author, is determined by the line of inter- 

 section of the plane of the vein with the boundaries of the ferru- 

 ginous portions of the beds. 



XL VI. Intelligence and Miscellaneous Articles. 



ON THE EMISSION AND ABSORPTION OF HEAT RADIATED AT LOW] 

 TEMPERATURES. BY G. MAGNUS. 



1. "pvlFFERENT substances, when heated to 150° C, emit dif- 

 I / ferent kinds of heat. 



2. There are bodies which emit only one kind of heat, and others 

 which emit several. 



3. To the first class belongs rock-salt when it is quite pure. Just 

 as the ignited vapour of this substance, or of one of its constituents 

 (sodium), only emits one colour, so, too, it only radiates one kind of 

 heat. It is monothermal, as its vapour is monochromatic. 



4. Rock-salt absorbs the heat radiated by rock-salt in larger quan- 

 tity, and more energetically, than that of sylvine (chloride of potas- 

 sium) and other kinds of heat. Hence, contrary to what Melloni 



* See Quart. Journ. Geol. Soc. vol. xxiv. p. 511. 



