352 



THE GEOLOGIST. 



Tertiary age. Unfortunately they were lost during their transmission to 

 England ; tbut the author gave a list of genera and of some species since 

 obtained. 



Manchester Geological Society. — June SOtJi. — Mr. Joseph Goodwin 

 presented to the Society two specimens of shale ; one from the Jet Amber 

 Mine, Haughton, containing minute shells of Anthracosia, and the other 

 from the Peacock Mine, Hyde, containing beautiful specimens of ferns 

 (Pecopteris), etc. A vote of thanks was passed to Mr. Goodwin for his 

 donation. 



A collection of fossil fishes, consisting of Megalichthys, Helodus, etc., 

 from the roof of the Spanish Juice or Half-yard Mine at Carr Knol, 

 near Oldham, was presented by Mr. John Butterworth, of Moorside, 

 Oldham. Mr. Wilde, of Moor Edge, sent for exhibition a fossil plant 

 found in the sandstone at Oldham Edge, which he thinks proves that 

 Halonia is but the root of Lepidodendron This connection of the two 

 plants, Mr. J. S. Dawes, F.G.S., of Smethwick House, asserted he had 

 proved many years since. 



The paper read was " On the Effect produced on Rowley Eag by Heat, 

 and the practical Application of its Products to useful Purposes," by Mr. 

 J. Plant. 



The author's object was to give an opportunity for the examination of a 

 series of specimens which were obtained from Mr. Henry Adcock, the in- 

 ventor and patentee of the Basaltic Stone Works at Oldbury, Worcester- 

 shire ; these works, and nearly all similar works for the conversion of 

 basalts and vitreous slags to ornamental purposes, having been discontinued, 

 opportunities will consequently rarely occur for the examination of the in- 

 teresting results of these experiments. 



The question as to the changes which heat has effected in the constitu- 

 tion and crystallization of certain igneous rocks has e^er been one of great 

 interest to the geologist ; and with a view to explain certain theories upon 

 the columnar structure and prismatic form of basalt, as observed generally, 

 but more especially at the Giant's Causeway, Staflfa, and the hill at Rowley 

 Regis, experiments were conducted as early as the year 1804, by Mr. 

 Gregory Watt ; which experiments established the fact that basalt and trap 

 were igneous rocks, and that the columnar structure of basalts could be 

 experimentally produced under certain conditions of heat and pressure. 

 Rowley Rag has been described by Senft as Melaphyre, an indistinctly 

 mixed rock, intermediate between ordinary greenstone and black basalt, of 

 dirty greenish-brown, hard and tough in a fresh state, having a specific 

 gravity of 2*85, and a composition of silica, 55 ; alumina. 25 ; oxides of 

 iron and manganese, 12 ; lime, 8 ; soda, 6 ; and inappreciable amounts of 

 potash and magnesia. Mr. Watt fused 700 cwt. of this material, and kept 

 it in a furnace several days after the fire was lowered. It fused into 

 a dark-coloured mass, of a vitreous character, with less heat than was 

 necessary to melt iron ; and a portion which was taken out whilst the mass 

 was in fusion, and cooled quickly, became perfectly glass}'. As refrigera- 

 tion proceeded in the mass it became changed into a stony substance, and 

 globules appeared ; these enlarged till they pressed laterally against each 

 other, and became converted into polygonal prisms. The most important 

 result observed was the formation of spheroids, sometimes extending to a 

 diameter of two inches. They were radiated with distinct fibres, in some- 

 what concentric layers ; but the centres of most of the spheroids became 

 perfectly compact before they attained the diameter of half an inch. This 

 structure gradually pervaded the whole body of the spheroid. A con- 



