DIY History | Transcribe | Scholarship at Iowa | Coal Measures and Coal Mining in Iowa, including paleontology and a discussion on the coal formation; also the methods of mining by Russell T. Hartman, 1898 | Coal Measures and Coal Mining in Iowa by Russell T. Hartman, 1898, Page 191

Transcribe
Translate

Coal Measures and Coal Mining in Iowa, including paleontology and a discussion on the coal formation; also the methods of mining by Russell T. Hartman, 1898

Coal Measures and Coal Mining in Iowa by Russell T. Hartman, 1898, Page 191

[page]191.[/page]

wedging. The former is in much more common use. The accompanying figure represents the process.

[image: two drawings of coal entries to the face of coal plus holes drilled for blasting powder; labels h, C, s; and h, C, u]
[caption]Fig. 8.A.[/caption]
[caption]Fig. 8.B.[/caption]
Fig. 8.A is the plan and B the elevation of the entry. Let C represent the face of the coal. The miner with his pick cuts out at the side the "shearing" (s) and at the bottom the "undercut" (u), then drills the hole (h) in which a charge of powder is placed. Upon firing the powder the coal is blasted into the "shearing" (s) and the "undercut" (u).
     In some of the Iowa miners machines are used in "shearing" and undercutting. The most successful machine for the Iowa field is the Harrison compressed air machine in which the compressed

Saving...

[page]191.[/page] wedging. The former is in much more common use. The accompanying figure represents the process. [image: two drawings of coal entries to the face of coal plus holes drilled for blasting powder; labels h, C, s; and h, C, u] [caption]Fig. 8.A.[/caption] [caption]Fig. 8.B.[/caption] Fig. 8.A is the plan and B the elevation of the entry. Let C represent the face of the coal. The miner with his pick cuts out at the side the "shearing" (s) and at the bottom the "undercut" (u), then drills the hole (h) in which a charge of powder is placed. Upon firing the powder the coal is blasted into the "shearing" (s) and the "undercut" (u). In some of the Iowa miners machines are used in "shearing" and undercutting. The most successful machine for the Iowa field is the Harrison compressed air machine in which the compressed