STATE GEOLOGIST. . 249 
steam shovel. These are made in various sizes, handling from 400 to 5,006 
cubic yards per ten hours. For cement works the smaller shovels 
handling from 400 to 800 cubic yards in ten hours will be of sufficient 
capacity. If the steam shovel is to be used for shale the bucket must 
be provided with sharp steel teeth for first cutting the shale, after which 
the material is shoveled into the car. The bucket capacity should be 
34 or I cubic yard. The cost of winning material by this method 1s 
probably from 5 to 12 cents per cubic yard. 
Dredging.—Dredging is practiced in obtaining clay from river or 
lake bottoms or in very wet, low country, as in the lake region of Michi- 
gan and Indiana. It would seem that for this work a continuous bucket 
dredge would be preferable to the ordinary dipper dredge, as it would 
enable the manufacturers to dredge deeper. The writer has, however, 
- seen a barge dipper dredge working to a depth of thirty feet without any 
difficulty. The cost of dredging in this manner is not great, probably not 
over 4 cents per cubic yard of 58 per cent. moisture, which is equivalent 
roughly to 134 barrels of cement. 
Mining. —Mining is practiced only where absolutely necessary, and 
is not carried on at any cement works to the knowledge of the writer, 
though there is no reason why it should not be undertaken if necessary. 
In mining, the main requisite is a strong thick stratum overhead, prefer- 
ably sandstone. A clay roof is dangerous and causes expensive mining. 
The cost of mining is always heavy, from 50 cents to 75 cents per ton, 
depending on the thickness of the vein, nature of roof and floor, hard- 
ness of the rock, mechanical aids available, etc. The cost of the dead 
work, track, posts and timbers is about 25 cents per ton, varying with 
the locality, etc. 
WINNING OF LIME MATERIALS. 
The methods of winning the calcareous materials according to their 
character may be classified as: 
I. Quarrying. 
2,  \Dyredleiones, 
3. Steam shovel work. 
4. Mining. 
Quarrying.—Ouarrying is applied, of course, only in working lime- 
stones or cement rock and needs no detailed description. Power drills 
should be employed, worked either by compressed air, steam or electricity. 
It is rather difficult to give general figures of the cost of ES but 
probably 20 cents per ton is not far from the truth. 
Dredging.—Dredging is practiced in winning the calcareous marls 
of Michigan, Indiana and Ohio. The amount of high calcium marl 
required for one barrel of cement varies from 8 to 12 cubic feet, with 
