OBSERVATIONS ON STONE-CHIPPING. 891 



and crushing action of drift logs or rolliug bowlders, wouUl furnish many 

 suggestive forms and shapes that a little ingenuity would apply, and 

 out of which would naturally grow the art of flaking. 



The streets of Paducah, Ky., are paved with partly rounded, angular, 

 silicious gravel, mostly of jasper. Seeing heaps of this ready for spread- 

 ing, I was struck by the many forms, mostly highly water polished, that 

 if found on a flaking ground would pass for refuse flakes and rubbish 

 left by the workmen. 



On inquiry I was informed that this coarse gravel was from banks 

 on the Tennessee Eiver above the ordinary overflows. I selected many 

 forms that any archaeologist would pronounce to be the work of man. 



A heavy wagon, loaded with hogsheads of tobacco, drawn by five or 

 six yoke of oxen, passed over the fresh-spread gravel with a sharp, 

 crushing, grinding sound. On examining the wheel tracks I was sur- 

 prised to find the slight impression the iron tire had made on the sur- 

 face stones. They had been pressed aside from the wheels, leaving a 

 slight rut, those under the wheels compressed together, but very little 

 broken ; not sufficient to account for the sharp, crackling noise made as 

 the wagon-wheels passed over them. On examining the effect from the 

 tread of the wheels to the old road-bed, a depth of about 6 inches, I 

 found most of the larger gravel stones under the top layer split, some into 

 flakes, the fractures in various directions, some crossing others. This 

 spread from the width of the wheel-tires to about three times as wide 

 on the old road-bed. Many of the fresh fractures presented the forms 

 and appearance of genuine cores, and would be mistaken for the work 

 of man. It was a beautiful illustration of the efiect of pressure on small 

 points of contact. Our lady friends, often inveterate iced-tea drinkers, 

 when they find a lump of ice too large for their glass, will, with a com- 

 mon toilet-pin between thumb and finger, press its point into the ice, tap 

 its head with the handle of a case-knife, or give it a click with a thimble. 

 The cohesion is destroyed and the ice splits with just such a fracture 

 as is made by impulsive point pressure on the more tenacious and re- 

 factory chert. 



These Paducah observations led to con siderable investigation as to 

 the action of lodged drift-logs on gravel-bars, and finally to an experi- 

 ment that I should recommend the Smithsonian Institution to try on 

 more extensive scale than I was able to. 



I filled a metal cylinder with pebbles of various sizes and shapes, 

 brought a pressure by a screw on them through a plunger; immediately 

 a crepitating sound was heard, which as the pressure increased became 

 sharper and louder, at times almost explosive, as the interstices became 

 filled with broken fragments, j^roducing side pressure and cross fract- 

 ures. The sound became more confused and died away. On emptying 

 the cylinder, the result was many representations of the rude imple- 

 ments found in the drift. 



