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practice to obtain a ready facility in the discrimination of 

 flint fractures. It is commonly said that this peculiar form 

 of fracture may easily be seen by anyone who takes the 

 trouble to examine a locaHty where flints are abundant. 

 Believing, however, that this is not the case, I will endeavour 

 as briefly as possible to give you a reason for my behef. 

 Those who are unwilling to trace any design in the form of 

 these flints, attribute the fractures to natural causes. Now 

 these may be divided into causes arising from the action of 

 either water, frost, or heat. 



First, let us consider the action of water ; taking the sea as 

 the most powerful agent, do we find " cores" and " flakes," 

 similar to those exhibited this evening, on any flint pebble 

 beach of the existing period ? Look at the sea in its most 

 majestic and savage gtate, when the huge breakers, rolling on 

 with irresistible fury, lash the coast in one long line of boil- 

 ing foam. Tons of cliflf may fall before its undermining 

 power ; huge masses of limestone weighing from two to five 

 tons each may be carried along from one place to another 

 (as indeed actually occurred from the northern to the 

 southern slope of the Plymouth breakwater) by its trans- 

 porting power ; but neither of these agencies can form 

 a " flake," and it is doubted whether they could even 

 fracture a flint. The action of the breakers is that of 

 povMding or grinding. Witness the belts of gravel and 

 sand along the shore at low water mark. Look closely at 

 this gravel and sand — chips there may be, but the chips are 

 rounded and ground. The gravel has all its little roughnesses 

 and angles worn smooth, and the grains of sand, when viewed 

 through a good lens, present the same appearance. The 

 waves may hurl one pebble against another. Ekamine this 

 pebble closely ; you will see it studded over with little con- 

 centric circles, and possibly a small bit knocked off an angle 

 here and there ; but the general appearance is that of semi 



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