POSSUM RIDGE MINE.

The Possum Ridge mine is similar in production and extent of workings to the Pond Creek mine but the coal lies deeper, being 357 feet below surface at the shaft, and is 9 to 10 feet thick. The returns are from east and west sides with about two-thirds of the workings on the west side.

On March 18, the main west return 350 feet southwest of the shaft was found to carry 31,724 cubic feet of air per minute, which contained 1.19 per cent methane and 0.20 per cent carbon dioxide. The volume of methane in this return was 377 cubic feet a minute, which is the highest found in any of the mines visited in this district. The cause of the great volume of methane from the west workings was not apparent and its existence there was not known to the operators. Sixty-five miners were working on the west side.

The main east return 350 feet southeast of the shaft carried 20,237 feet of air which contained 0.07 per cent methane or 14 cubic feet a minute, and 0.08 per cent carbon dioxide. Thirty miners worked on the east side.

REND NO. 2 MINE.

The Rend No. 2 mine presented conditions closely similar to those in the other two mines. The depth at the shaft was 215 feet, 71⁄2 to 8 feet of coal was removed, the output was 2,000 tons a day, and 175 miners were employed. There were two main returns, one from the west and one from the east workings, but there was much admixture of air back in the mine. On March 18, the main west return just west of the shaft carried 59,160 cubic feet of air per minute, which contained 0.05 per cent methane, or 29 cubic feet a minute, and 0.06 per cent carbon dioxide; and the main east return, 20 feet east of the shaft, carried 47,600 feet of air containing 0.07 per cent methane or 33 cubic feet a minute, and 0.03 per cent carbon dioxide. An air current of about 14,000 feet comes to the shaft through a pump hole, about half from the east and half from the west. If it be assumed that this return carried an average of about 0.06 per cent methane or 8 cubic feet per minute the total methane in the returns was 71 cubic feet a minute. Gas was given off in large amounts in the south and east entries which are on an upgrade. Several small faults were somewhat gaseous, one of them especially so.

MINES NORTH OF CARTERVILLE.

There are large mines at frequent intervals north of Carterville following the Herrin coal down the north sloping monocline. In the first one, the Burr C, a mile out of town, the coal is at a depth of 100 feet, whereas the coal in the No. 8 mine of the Big Muddy Coal & Iron Co., which is 5 miles north, is 169 feet below the surface.

BURR C MINE.

At the Burr C mine, which had an output of 1,500 to 1,600 tons a day, the return was in two main currents, which were measured and sampled on March 5, 1912. The main east return 1,300 feet east of the shaft carried 11,200 cubic feet of air per minute, containing 0.06 per cent methane, or 62 cubic feet a minute, and 0.26 per cent carbon dioxide. This air ventilated the south half of the east side of the mine or about one-fourth of the area of active workings, in which 53 miners were employed. The return air from the main west and the north half of the east-side workings, which was sampled 1,000 feet east of the shaft, ventilated about three-fourths of the workings, in which 130 miners were employed. The volume was 47,500 cubic feet of air and it contained 0.01 per cent methane or 4 cubic feet a minute, and 0.11 per cent carbon dioxide. The smaller volume of methane in this return as compared with that from the area of smaller workings on the east side is a notable feature.

MADISON NO. 8 MINE.

The Madison No. 8 mine is a mile north of the Burr C mine. About 180 miners were employed, and the output averaged nearly 1,500 tons a day. The depth at the shaft was 100 feet. The air of the main return was sampled 10 feet west of the hoisting shaft and measured at several places in the vicinity. The total volume of upcast air was 96,517 cubic feet per minute, of which about 30,000 feet escaped through an old shaft. The return air at the shaft contained 0.01 per cent methane or 9 cubic feet a minute, and 0.15 per cent of carbon dioxide.

MADISON NO. 9 MINE.

The Madison No. 9 mine is 2 miles north of the No. 8 mine and the shaft was 120 feet deep. The mine was larger than the others, having an output of 2,500 tons a day. Seven and one-half feet of coal was mined. The main returns were in two airways, one from the west half of the mine, in which 200 miners were employed, and the other from the east half, in which 150 miners were employed. The main west return air was sampled 250 feet west of the shaft and carried 58,743 cubic feet of air, which contained 0.06 per cent. methane, or 35 cubic feet a minute, and 0.09 per cent carbon dioxide. The east return, at the overcast 350 feet east and south of the shaft, carried 48,858 feet of air, which contained 0.07 per cent methane, or 34 cubic feet a minute, and 0.12 per cent carbon dioxide. The uniformity in amounts of methane on the two sides of the mine and the much greater amount as compared to that in the other mines south are noteworthy features.

Some gas was given off in the east-side workings and on the west side there was a feeder that burned continuously with a blaze 2 feet high. No gas was reported in drill holes. Most of the notable gas is in narrow zones of soft, wet coal extending across the mine and it appears to issue from the bottom clay.

C. & B. M. MINE.

The C. & B. M. mine of the Carterville & Big Muddy Co. is a short distance northeast of Cambria, or 14 miles northwest of the Burr C mine. The depth was 86 feet at the shaft and 7 to 8 feet of coal was mined from a 10-foot bed. The output was 900 to 1,100 tons, which was mined by about 150 miners. The return air from all but a very small part of the workings was sampled just below the southwest entry 1,800 feet north of the shaft. The return air had a volume of 36,000 feet and it contained 0.02 per cent methane, or 7 cubic feet a minute, and 0.22 per cent carbon dioxide. The air not represented in the sample was a current of about 4,000 cubic feet, ventilating workings in which 6 miners were taking down coal. The air passed into the upcast farther up the slope. No gas has ever been noted in this mine.

MINES NO. 7 AND NO. 8 OF THE BIG MUDDY COAL & IRON CO.

The two large mines of the Big Muddy Coal & Iron Co., mine No. 7, 1 mile east of Herrin, and mine No. 8, 3 miles northwest of Herrin, are in the Herrin coal bed.

Mine No. 8.-Mine No. 8 produces about 2,500 tons a day. The coal is at a depth of 170 feet near the shaft and 73 feet was mined in most of the workings. The return air came to the upcast in two main airways, one from the eastern part and the other from the western part of the mine, although there was a slight mingling of the ventilation far back in the workings. Little gas was found in the mine and most of it was in the top coal and never in the holes or undercuts. Some time previous to the date of sampling a small blower, which lasted two months, developed in the top in the second southeast entry. The east return, sampled at a point 195 feet east and 190 feet south of the shaft, carried 41,580 feet of air which contained 0.21 per cent methane, or slightly more than 87 cubic feet a minute, and 0.36 per cent carbon dioxide. The west return, sampled at a point 195 feet west and 190 feet south of the shaft, carried 36,190 feet of air which contained 0.14 per cent methane, or 51 cubic feet a minute, and 0.24 per cent carbon dioxide. The total volume of methane coming from this mine was about 139 cubic feet a minute.

Mine No. 7.-Mine No. 7, east of Herrin, was visited on March 18 and again on April 10, 11 days after mining had ceased. The output of this mine was about 2,000 tons a day. The coal is at a depth

of 150 feet near the shaft and about 7 feet was mined. The air in this mine was carried to the upcast by four principal airways, each one bringing the ventilation of about one-quarter of the mine. The tests of these returns gave the following results:

Methane and carbon dioxide in return-air samples collected in March and April, 1912, from mine No. 7.

The variations in methane emanation from the four quarters of this mine are somewhat notable. Seemingly the south half was producing less gas than the north half, due allowance being made for the smaller extent of the fresh workings. These differences continued after the cessation of mining, when the total methane emanation diminished to nearly one-half. If the large area of the mine be taken into consideration the amount of methane is remarkably small, and if the relative area of coal surface were made the basis of comparison the mine would show probably less methane per square foot than other mines of the same depth.

The mines at Bush and Royalton illustrated the conditions in the Herrin coal field in the northwest corner of Williamson County and the adjoining southwest corner of Franklin County. The strata dip northeast, but at Bush there is a local synclinal flexure in the general monocline.

Bush mine.-The Bush mine is a moderately large one, about 250 miners being employed and the daily production being 1,500 tons. The coal is 7 to 9 feet thick and lies 118 feet below the surface at the shaft. No appreciable amount of gas had ever been noted in the mine. The most extensive workings were on the east and north

sides. The main returns were east and west, but the currents from either side mixed somewhat far back in the mine. On March 25, 1912, the east return just east of the shaft carried 24,200 cubic feet of air per minute which contained 0.01 per cent methane and 0.22 per cent carbon dioxide. The main west return 350 feet west of the shaft carried 45,738 feet of air which contained 0.02 per cent methane and 0.34 per cent carbon dioxide. The volume of methane per minute was 24 feet on the east side and 9 feet on the west side.

Royalton mines.-The south and north mines at Royalton reach the coal at depths of 212 and 315 feet, respectively, the measures having a moderately steep dip to the north. The coal is 9 feet thick. The south mine was a small one with an output of 250 tons a day, and the north mine produced about 1,600 tons a day. Both mines were visited on March 25, 1912.

The total return of the south mine sampled near the shaft carried 41,395 feet of air which contained 0.03 per cent methane, or 12 cubic feet a minute, and 0.06 per cent carbon dioxide. No gas had ever been observed in making lamp tests in this mine. At the north mine a mile north, which was more than 100 feet deeper, gas appeared in the drill holes and in such volume at the working faces that bratticing had to be kept up close. The mine had been in operation only two years, so that there were no old workings. The returns were in two airways, each representing about half of the mine, and there were 90 miners on each side. The southwest return 100 feet southwest of the shaft carried 16,170 cubic feet of air per minute which contained 0.09 per cent methane, or 141⁄2 cubic feet a minute, and 0.21 per cent carbon dioxide. The southeast return, sampled 350 feet southeast of the shaft, carried 6,000 feet of air which contained 0.36 per cent methane, or 21 cubic feet a minute, and 0.10 per cent carbon dioxide. The reason for the greater volume of methane on the southeast side was not apparent.

HALLIDAYBORO MINE.

The Hallidayboro mine is far away from other mines in the Herrin bed. Its depth is 160 feet at the shaft and from 7 to 10 feet of coal was taken out. The output was about 1,200 tons a day. At the time of the author's visit on March 19, 1912, there were two main returns, one from the east, ventilating about three-fifths of the mine, and one from the west, ventilating two-fifths of the mine; 80 miners were employed in the east return and 45 in the west. The main east return 600 feet east of the shaft carried 23,100 cubic feet of air which contained 0.06 per cent methane, or 14 cubic feet a minute, and 0.16 per cent carbon dioxide. The main west return, sampled 600 feet west of the shaft, carried 19,200 feet of air which contained 0.08 per cent methane, or 15 cubic feet a minute, and 0.26 per cent of carbon dioxide. It will be noted that the volume of