32 DAVENPORT ACADEMY OK NATURAL SCIENCES. 



order to give the implement its peculiar shape. The results of my 

 labor were as follows : Length of stroke, ten inches ; width of groove, 

 two to two and one-half inches, the groove being deepest in the center 

 of the stroke, where the greatest pressure was unavoidably brought to 

 bear, and the ends sloping and rounded. Repeating the process with- 

 out changing my position, a character corresponding to Fig. 3 was 

 formed. Reversing the tool and resuming operations, Fig. 10 (having 

 ends more acute than Fig. 3) was reproduced. Ne.xt selecting a large 

 circular or semi-oval implement, I proceeded with the grinding as in the 

 other instances, being governed in my operations not by a desire to re- 

 produce the forms upon the rock, but by the shape of the implement. 

 The result of this last operation corresponds with Fig. 8, the whole 

 bearing a close resemblance to the pictographs upon the rock, differing 

 from them only in length and width, and that but slightly. It will be 

 seen by inspection that the complicated forms are simply the result of 

 a grouping of the two primary or simple forms of designs, as Figs. 4, 8, 

 and 15. Several repetitions of these simple forms, from a central 

 point, governed by such slight changes in his position as the laborer 

 would almost unconsciously assume for the purpose of rest or with a 

 view to reach a fresh grinding surface, would naturally and almost un- 

 avoidably result in the production of such forms as Figs. 2, 3, 4, 7, lo, 

 16, and 17. Figs, i, 11, 12, 13, 18, 19, and 20 are, i)erhaps, due to the 

 efforts of several individuals laboring together. That these markings 

 are not incisions, but the result of abrasion, is evident from the regu 

 larity of the form, the rounded outline of the ends, and the smooth and 

 sloping finish of the interior of each. 



