baɪ ðə stˈɑːɹt ʌvðə twˈɛntiəθ sˈɛntʃɚɹi, ðə mˈaɪnz ɛmplˈɔɪd ɐbˌaʊt wˈʌnhˈʌndɹɪd fˈɪfti mˈɛn ænd pɹədˈuːst ɐbˌaʊt θɹˈiːhˈʌndɹɪd tˈʌnz ʌv kˈoʊl ˈiːtʃ dˈeɪ.
By the start of the 20th century, the mines employed about 150 men and produced about 300 tonnes of coal each day.