220 



Frank Cramer — Recent Rock Flexure. 



Art. XXIX. — On a recent Rock-Flexure ; by Frank Cramer. 



The Combined Locks pulp mill, located on the Lower Fox 

 River, about six miles northeast of Appleton, Wis., is a long, 

 low stone building (about 40 by 248 feet), and set below a head 

 of seventeen feet of water. The direction of its long axis is 

 northwest and southeast. The river flows at right angles to 

 this axis until it passes the end of the mill, and immediately 

 turns east and flows to a point a short distance beyond the mill, 

 where it turns to the north. At about eight o'clock on the 

 morning of the Tth of September, 1889, an accident involving 

 considerable damage happened to this mill. 



A solid cement pier, 14 feet through at the top and 16 feet 

 through at the bottom, forms the end of the great .dam and 

 the river-end wall of the mill as far as the eaves. Upon this, 

 at its inner edge, is set a two-foot wall which supports the shed 

 roof of the mill. This solid stone pier (P, tig. 1) was cracked 

 from side to side and from top to bottom, and the nearly per- 

 pendicular crack gaped between one and two inches at the top 

 and almost none at the bottom. The northeast (down-river) 



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Fig. 1. Diagram showing N".W. end wall and N.E. side wall of 

 mill, with floor in position ; other walls and roof omitted. P, ce- 

 ment pier, a, b, c, etc., pulp-grinders, 1, 2, 3, etc., windows. Total 

 length of building, 248 feet. 



wall of the mill, running at right angles to the pier, was 

 broken by a symmetrical set of cracks which indicate that the 

 line of disturbance passed under this wall 94 feet from the 

 pier. At this distance there is a perpendicular crack under 

 the sixth window (n, fig. 1) One or two smaller cracks run 

 parallel with it. On each side of this crack there are a num- 

 ber of cracks inclined at an angle of 45 degrees, their lower 

 ends directed toward this perpendicular crack. The cracks on 

 the two sides are nearly equal in number, at nearly equal dis- 

 tances from each other, and mar the wall to a distance of about 

 30 feet each side of the sixth window. 



