229 



Dr. Hare had prepared a communication for the American Journal 

 of Science, in which he hoped to justify his summary statement of 

 Dove's errors. 



Prof. Henry communicated, orally, an extension of the expe- 

 riments, which he had previously brought before the Society, 

 on electro-dynamic induction. He had succeeded in magneti- 

 zing needles by the secondary current in a wire more than two 

 hundred and twenty feet distant from the wire through which 

 the primary current was passing, excited by a single spark 

 from an electrical machine. 



Mr. Lea called the attention of the Society to two specimens 

 of coal, taken from the large anthracite coal bed in the Pine 

 Grove district. 



One of the specimens was remarkable for its regular rhombic form, 

 in which all the angles were 70° and 110°, the cleavage of each plane 

 being nearly perfect. The other was part of a large specimen of car- 

 bon, scarcely changed from its condition as charcoal, the loose fibrous 

 structure being nearly perfect, and the whole having very thin lamina? 

 of pure anthracite, parallel with the fibre. 



A portion only (2 or 3 feet) of this large bed, the dip of which is 

 about 35°, presented the oblique cleavage, preserving that character 

 throughout as far as could be observed. 



Mr. Lea then made some observations on the disturbed condition 

 of the whole of the southern coal field, and read a portion of a letter 

 from the Athenaeum, addressed by Mr. Lyell to Dr. Fitton, where he 

 states that the conversion from the bituminous to the anthracite con- 

 dition is " most complete where the beds have been most disturbed." 



Mr. Lea did not think this was the case throughout this coal field ; 

 for Mr. Lyell seemed to have overlooked the fact, as shown in the 

 sections of Mr. Taylor's reports on that part which passes through 

 the county of Dauphin, and known generally to our geologists, that 

 this, like the coal field of South Wales, insensibly graduates into bi- 

 tuminous coal. Such is the fact as we proceed westward in the 

 southern coal field of Pennsylvania, the bitumen being yielded up in 

 the more eastern part, as stated by Mr. Taylor, Prof. Silliman, and 

 other geologists. 



It is well known that the conglomerates and coal beds of Sharp 

 Mountain (the southern border of this coal field) are nearly vertical 

 at Tamaqua, Pottsville, Pinegrove, Goldmine Gap, Ranch Gap, Yel- 

 low Spring Gap, and Rattling Run Gap; but there is a great differ- 



