Show heavy coal producers tho the concentration of the anthracite an th Indu industry str of pennsylvania into strong and ivil few units Is eborn by the fact that in 1911 nearly 76 per cent of the mines bere iere ere producers of more thin than tons each md ind that all but 3 per cent of the total prodoc tion vas nas from this group ot of mines according to the geological euric tile the anthracite mines exclusive in the filat class aboe producing over tons each cach fielded sa 87 2 per of the total output and the acs mines included dod in fit tills this clao hid bid in average production of tons each cich in 1910 there 11 eie anthracite inthia mines itzell illies in the ton cliss class and their r at earlge production nas is tinb each in 1909 1903 mines hid an aier uge production of csc tons each I 1 |