The Mother Lode region of California . put in, from 28 to 35 in number,without taking down the machines. The holes are drilled from 5 to 6feet vertically. The manner of pointing these holes is shown in the 54 CALIFORNIA STATE MINING BUREAU. accompanying diagram (Fig. 9). There is no hand-drilling, all workof squaring-up, etc., being done with machines. In this shaft 26 menare employed. The shaft is timbered throughout with 12x12 Oregonpine; sets 5 feet from center to center near the top, and in the lowerportion 6 feet from center to center. The accompanying illustration(Fig. 10) shows the rela
The Mother Lode region of California . put in, from 28 to 35 in number,without taking down the machines. The holes are drilled from 5 to 6feet vertically. The manner of pointing these holes is shown in the 54 CALIFORNIA STATE MINING BUREAU. accompanying diagram (Fig. 9). There is no hand-drilling, all workof squaring-up, etc., being done with machines. In this shaft 26 menare employed. The shaft is timbered throughout with 12x12 Oregonpine; sets 5 feet from center to center near the top, and in the lowerportion 6 feet from center to center. The accompanying illustration(Fig. 10) shows the relation of the strike of the rocks to the position ofthe shaft. (Notice also the strike of rocks in the Oneida and Wildmanshafts in this county—see Figs. 14 and 21.) An unusual feature in the new Kennedy shaft, not often found inshafts sunk in hard rock, is the bridge used in timbering; this is illus-trated in the accompanying sketches (Figs. 11 and 12). It was claimedby Mr. George W. C. Glass, who was in charge of this work, that this. Sh{E:TCM sho^inS ^3tnr)&r oj^ falacino MachiM&^HouEs Fig. 9. method of shaft-timbering greatly expedited matters and was lessexpensive than by the ordinary method. This manner of timberingshafts is not novel, but is usually employed in soft and not in hardground; but as the bridges have been carried from top to bottom inthis shaft, and as good headway has been made throughout, it is prob-able that this method has given entire satisfaction in this instance. The Kennedy Mill.—This mill contains 40 stamps, and is in chargeof Mr. Webb Smith. The monthly capacity is about 4,000 tons. Thestamps drop 7-J inches 95 times per minute. The height of discharge isfrom 8 to 10 inches, three differential chuck-blocks being employed tokeep these as nearly uniform as possible. The grade of the plates is 1^inches to 12; 24-mesh brass wire screen is used in the battery, THE MOTHER LODE REGION—AMADOR COUNTY. 55 formerly 30-mesh. The amount of water employed in t
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectminesandmineralresou
