easily, and have a tendency to melt in a hot fire; and the shade of color in the ash is a pretty good indication of the character of the coal in this respect. Extent of the Deposits.-It is probable that the present anthracite fields of Pennsylvania are but the remnants of a great body of coal which once included them all and filled up the spaces between them, the missing portions having disappeared through denudation. The writer's observations of the geology of the district show that this ancient coal-field must have had an area of about 2000 square miles, and, supposing that all the present beds were coextensive with it, contained about 92,840,960,000 tons. The amount of coal available at the beginning of the historic period was. about 26,721,093,817 tons, of which 409,597,748 tons were mined and sent to market in the sixty years from 1820 to 1880, inclusive, as shown in Plate X.

The white-ash series of anthracite beds has four members-the Buck Mountain, Skidmore, Mammoth, and Holmes, or B, D, E, and F. (See fig. 4.) Another bed, 5 feet in thickness, called the Ross bed, has been traced in some places, and named "C" by some writers, but it is scarcely extensive or distinct enough to have a separate designation. (See figs. 6, 7, 8, 9, 10.) An outlying branch of the Mammoth bed is also counted separately sometimes, and called the "Seven-foot," from its usual thickness, but it is more properly credited to the great bed with which it is immediately connected. The first in the group, B, or the Buck Mountain bed, has received little attention as yet in the First coal-field, where it averages 8 feet in thickness, though its coal is of good quality. In the Lehigh region and the western end of the Third field it becomes very important, being 16 feet in thickness at the Buck Mountain mines, at the extreme eastern end of the Second field, and increasing to a thickness of sometimes 25 to 30 feet in the central portion. In the vicinity of Scranton, in the Third field, it is only 4 feet thick. On the other hand, its neighbor, the Skidmore, Wharton (or D) bed, is 8 feet thick at Scranton, and contains excellent coal; in the Mahanoy field it is usually 10 feet thick, while in the Schuylkill region it is but 6 feet thick, and its coal is often so rough and slaty as to be unmarketable. The Mammoth bed (E) is the great bed of the anthracite regions, and produces much more of the coal sent to market than all the other beds combined. (See fig. 5.) Its thickness varies from 14 feet or less in the Scranton district, to 20 in the Wyoming, and from 20 to 40 in the Mahanoy district, and to much more in local enlargements, but its average thickness is 25 feet. It is the bed sought after by all miners, and other beds are opened only when the section of the Mammoth within the operator's territory is being exhausted. It yields a hard, white-ash coal of great purity, which is in demand for furnace use and for other purposes requiring a clear, hot fire. The Holmes bed (F) lies about 100 feet above the Mammoth. It contains from 4 to 6 feet of hard, compact, short-grained, white-ash coal, well adapted for furnace use. The Primrose (or G) bed is 10 feet thick, and produces a gray-ash coal, softer than that of the Mammoth, but excellent for housekeepers' use. Farther west this bed becomes the famous Pittsburg bed (or H) of the bituminous coal-field.

The measures of the Southern coal-field are shown in the accompanying cross-section of the Philadelphia and Reading Coal and Iron Co.'s shaft near Pottsville, Pa (Plate XII.). This shaft, near the south foot of the great anticlinal axis of Mine Hill, is the deepest cut in the anthracite coal-measures of the United States,

313

developing a greater thickness of coal-strata and coalbeds than any other shaft in the world. It is located on the east branch of Norwegian Creek, on a lateral branch of the Philadelphia and Reading Railroad, 96 miles by rail from tide-water at Philadelphia. Its mouth is 729 feet above tide-level. The shaft was sunk 108 feet to the Peach Mountain bed, 10 feet thick, one of the Upper red-ash coal series; thence down 431 feet, where the Little Tracy was found, 45 feet thick, much beyond its usual size; at 1100 feet the Diamond bed was cut, 16 feet thick, also much enlarged; at 1559 feet the shaft had passed through all the red-ash coal-beds to the Primrose or gray-ash bed, 17 feet thick, five feet more than its ordinary size; at 1600 feet, the bottom of the shaft, a bore-hole was put down 376 feet to the bottom of the Mammoth coal-bed, here 21 feet thickmaking a total depth of 1976 feet, and cutting thirtytwo coal-beds in all, twenty-three of which were over 2 feet thick-making

The capacity of production referred to means the probable output with present force and appliances.

The following summary, from the early census reports of 1890, will serve to show the increase in coal production, etc., during the last decade: Total production of anthracite coal during the calendar year 1889, 40,665,152 tons; number of employés, 125.229; total amount paid in wages, $39,152, 124; quantity of coal shipped to market, 35,407,710 tons; quantity used in vicinity of mines, 4,848,276 tons; average number of working days 194; number of collieries, 342; value of product at mines, $65,718,165. The largest amount shipped in any one year (1888) was 38,145,178 tons.