POPULAR SCIENCE 601 



well-marked glaze. This results in the formation of a somewhat 

 vitreous surface which the author found was susceptible to 

 shattering under the pressure of a moving point (fig. 4). 



His experiments showed that this glazed surface is perhaps 

 a little harder than that of the specimens showing the least 

 amount of patination, that those more patinated are still softer, 

 and that the softest of all are those in which the patination had 

 progressed to the white stage. In the case of these latter 

 specimens it was found to be possible to cut into their surfaces 

 and produce well-marked grooves with comparative ease 

 (fig. 5). These experiments demonstrated clearly that newly 

 broken, sound, unpatinated flint is very hard, 1 that other 

 patinated examples are in a much softer condition, and that 

 with no great pressure it was possible to impose lines of shatter- 

 ing upon these latter specimens. 



As also the flints scratched under natural conditions and 

 selected for examination had evidently been patinated before 

 they were scratched, and as most of the striae showed evidences 

 of " weathering out," it became apparent that it was not neces- 

 sary to suppose that they had been subjected to very great 

 pressure, and that the wide and deep striae developed upon the 

 thin flakes of flint were in all probability simply "weathered out" 

 scratches, the initial stages of which did not require verv great 

 pressure to produce. To put this question of the weathering out 

 of scratches to some sort of test, the author experimented with a 

 flint found upon the surface of the ground at Westleton, Suffolk. 



This specimen showed upon its surface a line of shattering 

 about an inch in length, and by the use of a small steel probe the 

 shattered material was easily removed for the distance of half 

 an inch and a well-marked groove produced. Thus this par- 

 ticular striation is now composed of a line of shattering over 

 half its length (fig. 6), the other half being represented by a 

 most obvious cleft or groove (fig. 7). The author has examined 

 a very large number of striated flints, and with the exception of 

 one massive specimen found beneath the Norwich Crag, 8 all 



1 Experiments were conducted in which emery powder mixed with oil was 

 forcibly rubbed upon the surface of such flint, and after two hours' work only a 

 few very slight scratches were produced. 



3 This specimen showed a V-shaped cut in its surface, as though the agent of 

 striation had been able to cut right into the flint ; the striation showed little or no 

 signs of weathering. The ordinary weathered-out striae are more or less U-shaped 



