272 ANNUAL OF SCIENTIFIC DISCOVERY. 



es ; the great central tract, extending from Tuscaloosa, Alabama, to 

 the west of Pennsylvania, and being apparently continued to New 

 Brunswick and Nova Scotia; the second tract strikes northwestward 

 from Kentucky, crosses the Ohio, and stretches through Illinois to 

 the Mississippi River ; a third region, smaller than the others, lies 

 between the three great lakes, Erie, Huron, and Michigan. Com- 

 petent geologists affirm, that, from a comparison of the coal strata of 

 contiguous basins, these are no more than detached parts of a once 

 continuous deposit. 



The extent of this enormous coal-field is in length from northeast 

 to southwest more than 720 miles, and its greatest breadth about 180 

 miles; its area, upon a moderate calculation, amounts to 63,000 

 square miles ! In addition to these, there are several detached tracts 

 of anthracite in Eastern Pennsylvania, which form some of the most 

 remarkable coal-tracts in the world. They occupy an area of about 

 200 square miles. 



The strata which constitute this vast deposit comprehend nearly 

 all the known varieties of coal, from the dryest and most compact an- 

 thracite, to the most fusible and combustible common coal. One of 

 the most remarkable features of these coal-seams is their prodigious 

 bulk. The great bed of Pittsburg, extending nearly the entire length 

 of the Monongahela River, has been traced through a great elliptic 

 area of nearly 225 miles in its longest diameter, and of the maximum 

 breadth of about 100 miles, the superficial extent being 14,000 

 square miles, the thickness of the bed diminishing gradually from 

 12 or 14 feet to 2 feet. In 1847 the anthracite coal regions of Penn- 

 sylvania furnished 3,000,000 tons, and 11,439 vessels cleared from 

 Philadelphia in that year loaded with the article. The produce in 

 1848 and the present year is of course larger. 



The bituminous coal area of the United States is 133,132 square 

 miles, or one 17th part of the whole. The bituminous coal area 

 of British America is 18,000 square miles, or one 45th part; Great 

 Britain, 8,139 square miles; Spain, 3,408 square miles, or one 52d 

 part; France, 1,719 square miles, or one 118th part; and Belgium, 

 518 square miles, or one 122d part. The area of the Pennsylvania 

 anthracite coal formations is put down at 437 square miles ; and that 

 of Great Britain and Ireland, anthracite and culm, at 3,720 square 

 miles. The anthracite coal of Great Britain and Ireland, however, is 

 not nearly so valuable an article of fuel as the anthracite coal of 

 Pennsylvania, nor does a given area yield so much as the latter. 

 New York Express. 



IDENTITY OF SEVERAL DIFFERENTLY NAMED AMERICAN MIN- 

 ERALS. 



PROF. B. SILLIMAN, JR., by a series of investigations communi- 

 cated to the American Association and Sittimari's Journal, has 

 shown that several American minerals, known and described under 

 different names, are in reality identical. The mineral found dissem- 

 inated in the white limestone at Bolton, Mass., and to which Prof. 



