824 THE POPULAR SCIENCE MONTHLY. 



coarse outline design indicated the part to be removed. The labor 

 was executed either by sawing partly through the stone and deftly 

 breaking off the fragment, or by pecking it away with a flint-point. 

 Lastly, the surface of the planes was rubbed with flat stones or polish- 

 ers to remove the traces of the chippings. Other processes also appear 

 to have been employed. The artist drew his figure in coarse tracings, 

 and covered with ashes the lines he desired to bring out in relief. The 

 whole surface was then heated with fire ; the parts which were sub- 

 jected to the direct action of the flames were decomposed, and left 

 hollow places, while those that were protected by the ashes remained 

 intact.* 



For finishing his work, the sculptor had nothing better than a flint- 

 point or a copper chisel,f the only tools in use, for iron was unknown. 

 He was obliged, in order to execute those colossal figures and the bas- 

 reliefs which now make such an impression of astonishment upon us, 

 to cut with those imperfect tools in a very hard rock to a depth of 

 three or four centimetres. The fact of the performance of a labor of 

 such length is a certain indication of the infancy of the society in 

 which it was done, where man had not yet learned to appreciate the 

 value of time. 



The region of the piedras pintadas (painted stones) in South 

 America extends from Guiana to Patagonia. They are found in the 

 wilds of Brazil and La Plata as well as in the more civilized districts 

 of Peru and Chili, and they betray everywhere a remarkable analogy. 

 In the solitudes of Para and Piauhy, Brazil, are numerous intaglio- 

 sculptures, executed by unknown peoples ; they represent animals, 

 birds, and men, in various attitudes. Some of the men are tattooed ; 

 others wear crowns of feathers ; and the picture is finished off with 

 arabesques and scrolls. At la Sierra da Onca are drawings in red 

 ochre, isolated and in groups, without apparent order, and the rocks of 

 the province of Ceara and those of Tejuco are covered with tracings 

 not unlike those on the rocks of Scandinavia. Humboldt describes 

 intaglios on the right bank of the Orinoco, representing the sun and 

 moon, pumas, crocodiles, and serpents, ill-formed figures defined most 

 frequently by a simple outline and declaring little advancement in art. 

 Nevertheless, since they are cut in the hardest kind of granite, it is 



* Mr. Wiener saw the natives excavating an irrigation canal in the valley of Chi- 

 cama de Sausal, through a rock which stood in the way. The workmen piled ashes along 

 the line of the edges of the canal, covered them with dried manure and burned it. After 

 eight days they succeeded in forming by this process a channel through a granite rock 

 containing a vein of basalt 1'20 metre wide, 0*80 metre deep, and 2-30 metres long. 



\ There has been found near Quito a chisel that was used in working the large blocks 

 of trachyte employed in paving the roads of the Incas' empire. It weighed 198 grammes. 

 The surface was worn, the edge was nicked, and the head appeared to have been ham- 

 mered upon, all indicating that it had been subjected to long use. An analysis of a piece 

 of it by M. Damour gave ninety-five parts of copper, a little more than four parts of tin, 

 and slight traces of iron, lead, and silver.. 



