I02 ROCKS USED IN THE MANUFACTURE OF TRONATTAS. 



In other words, if the determination of the specific 

 gravity had been carried out in proportion to the fre- 

 quency of occurrence, I ought to have determined it off 

 i6 pieces of hornstone and 3 pieces of porcellanite for 

 every one piece of breccia, and others that I examined. 

 But instead of this I weighed only two pieces of horn- 

 s'tone (that is to say, one-eighth of the number that 

 should have been 'examined) for one piece of breccia and 

 others. 



This explains, therefore, the difference in the figures, 

 and it is obvious that those of the last table represent 

 the actual figures. If I therefore collect 100 tronatta 

 there will be 



Heavier than flint 76 specimens, composed of 70 

 hornstone, 3 breccia, 2 porcellanite, i other. 



Equal to flint 16 specimens, composed of 8 horn- 

 stone, I breccia, 5 porcellanite, i other. 



Lighter than flint 7 specimens, composed of o horn- 

 stone, o breccia, 5 porcellanite, 2 others. 



Therefore, taking weight for weight, 100 tronatta 

 were considerably heavier than 100 European imple- 

 ments of exactly the same size. 



The above investigation has conclusively proved that 

 there is a great variety of rocks used in the manufacture 

 of the tronatta. This variety of substances stands in a 

 sharp contrast to the monotony of the material used in 

 the manufacture of the European implements. For 

 eolithes and archaeolithes nothing else but the well- 

 known flint of cretaceous age was used, at least as far 

 as I can judge from the collections at my disposal. The 

 eolithes from the Mafflien, in Belgium, seem to form 

 the only exception, inasmuch as a dark blue hornstone,. 

 somewhat resembling that from Johnstone's or Hut- 

 chison's quarry, has been used. Variety of material and 

 monotony of the same are the chief distinguishing 

 feature of an otherwise undistinguisiiable collection of 

 eolithes and archaeolithes from Tasmanian and Europe. 



