September 24, 19 14] 



NATURE 



89 



The Large Non-Conchoidal Fracture-Surfaces of Early 

 Flint implements. 



When a representative series of flint implements is 

 examined comprising examples of everj- stage of cul- 

 ture from the Neolithic back to the earliest Chelles- 

 Palasolithic specimens, it will be observed that, gener- 

 ally speaking, tne older the implements the less thev 

 ^how small and "dilettante" flaking in their manu- 

 facture, and that when the earliest Chelles stage is 

 reached the flints have been fashioned by the removal 

 of large, bold flakes not supplemented by secondarv 

 work, such as is to be seen upon nearlv all the 



amplcs of later cultures. 



When a further series of implements is examined 



which predate the earliest Palaeolithic specimens, this 



peculiarity is seen to be still more marked, the flints 



many cases having been fashioned solely bv 



quartering " blows producing clean, fiat fracture- 

 surfaces exhibiting neither well-marked cones of per- 

 cussion nor conchoidal rippling, such as are so often 

 produced by the more ordinary 

 type of blow. If, as often hap- 

 pened in pre-PaliEoIithic times, an 

 implement was produced by 

 means of such blows, the flakes 

 would not in the first place ex- 

 hibit the normal characteristics 

 of human blows, and secondly, 

 many of these flakes would, in 

 the process of manufacturing the 

 implement, of necessity be trun- 

 cated and their resemblance to 

 accepted "human" flakes made 

 still smaller. Some of these trun- 

 cated flakes, moreover, at first 

 sight have the appearance of 

 being thermal breaks, and it re- 

 quires a close and intelligent 

 examination of their surfaces 

 with a high-power lens to discern 

 those small indications which 

 demonstrate that the flakes have 



been removed by blows. In addition to the cone of 

 percussion and conchoidal rippling which are often 

 produced by a blow upon a flint, fissures of varying 

 size are also formed which radiate from the point of 

 impact. 



Some of these fissures, which appear to me to repre- 

 sent "tears" made in the flint by the cleaving force 

 of the blow, are very minute, but in nearly every case 

 are capable of discernment with a really good lens. 

 I have found by experiment that the "quartering" 

 blow to which I have referred, though not producing a 

 well-marked cone of percussion, and ver\- frequently 

 no conchoidal rippling, nevertheless gives rise to these 

 small fissures, and that it is generally possible by the 

 evidence they afford to determine the exact " fractur- 

 ing agent " and the direction in which it has acted. 



It seems to me to be necessary- for the prehistorian 

 to recognise the real meaning of these peculiar frac- 

 ture-surfaces of early flint implements, and I think 

 their non-recognition has been the cause of the in- 

 ability of many observers to accept these specimens 

 as having been humanly fashioned. To those, how- 

 ever, who are familiar with the method of production 

 of such fracture-surfaces it becomes clear that great 

 precision and dexterity are needed to make an imple- 

 ment by means of this particular type of blow, and 

 that in consequence the probability of unguided 

 natural forces having produced them is practically 

 eliminated. 



J. Reid Moir. 



12 St. Edmund's Road, Ipswich, September 12. 



NO. 2343, VOL. 94] 



BRITISH AERONAUTICS.^ 



THE fact that methods of experiir.ent and the 

 apparatus used for test have become stan- 

 dardised has rendered it possible to add con- 

 siderably to the detailed knowledge relating to 

 aeronautics, and the result is reflected in the 

 increased size of the annual volume published by 

 the Advisory Committee for Aeronautics. The 

 amount of test-work still called for is enormous, 

 and for some time to come problems will need to 

 be taken in order of urgency, whilst many prob- 

 lems of great scientific interest are left for later 

 consideration. Amongst such problems may be 

 classed the mathematical investigation of motion 

 such as that illustrated in Fig. i, which shows a 

 photograph of fluid motion round a model of an 

 aeroplane wing. The photograph had a time- 

 exposure of about one second, and the lines indi- 



FlG. I. — Flow round aerofoil inclined at 16°. From "Technical Report of the Advisory Committee for 

 Aeronautics for the Year 1912-13." By permission of the Controller of H.M. Stationery Office. 



cate the direction of the flow, and their length the 

 mean velocity. So far no promising hydro- 

 dynamical analysis has been found for such a 

 flow. 



The report deals with quite different subjects, 

 and relates almost entirely to the experimental 

 determination of the forces and couples acting on 

 models immersed in a moving fluid. .\ consider- 

 able range is covered in relation to parts of aero- 

 planes, and it is now possible to make a good 

 prediction of the resistance of a new flying 

 machine from the resistances of its component 

 parts. One section of the report shows how 

 model results are applied to full-scale work at the 

 Royal Aircraft Factory. 



The ref>ort is concerned, on the model side, 

 almost entirely with results obtained in the new 

 four-foot channel at the National Physical Labora- 

 tory. The original channel, although very useful, 

 was not considered to be satisfactory apparatus 

 for the permanent equipment, and a series of ex- 

 periments on model channels and buildings was 

 undertaken in order to find, if possible, some 

 design for a channel which would lead to im- 

 proved steadiness of air-flow. The production of 



1 "The Technical Report of ihe Advisory Committee ior Aeronautics for 

 the year 1912-13." Pp 416. (London : Wyinan and Sons, Ltd., 1Q14. 

 Price los. 



