Publisher's Synopsis
Excerpt from Department of the Interior, Bureau of Mines Bulletin, 1915
The foregoing discussion of renewals deals with the depreciation of stoppings through normal mining conditions. There are, however, extraordinary agencies that destroy stoppings, some of these agencies partly or wholly wrecking certain types of stoppings and yet in no way injuring other types. Such agencies are: Fires, windy shots, blown - out shots, explosions, l'ocal roof falls, general mine squeezes, and water.
In order to obtain the annual expense for emergency repairs on the different kinds of mine stoppings, information was obtained from coal operators regarding the number of stoppings and the cost of repairs each year because of these extraordinary agencies The quotient obtained by dividing the total cost by the number of stop pings in use at the particular mine was charged to each stopping as the annual cost of emergency repairs. For example, at one mine the records showed that 18 stoppings wexe destroyed by windy or blown out shots; the cost of each repair averaged the total cost was and, as stoppings were in use, the expense to be dis tributed over each stopping was 12 cents per annum.
A compilation of the information obtained on the annual expense required for emergency repairs is given in Table 7 following.
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