A Rock-DrilL 



95 



The apparatus, which is simple and most effective, consists of 

 a solid piston working in a very strong cylinder and driven to 

 and fro by compressed air, whose action is regulated by a slide 

 valve. The drill is fitted directly into the end of the piston 

 rod, and by an ingenious arrangement it is made to perform a 

 partial movement of rotation during each backward motion, so 

 that it may strike the rock in a new direction each time. The 

 working pressure of air was 50 lbs. per square inch. We noted 

 the time while a boring was being made, and found that it took 

 exactly nine minutes to make a hole nine inches deep, through 

 the hard rock. The power is originated by a double-acting 

 steam-engine, situated at the inner extremity of the main adit 

 level, from whence a supply of compressed air is conveyed in 

 flexible pipes along the various tunnels in which boring is being 

 done. In subsequently blasting the rock, gunpowder is used in 

 preference to dynamite or other explosives, I believe on account 

 of the toughness of the ore, which therefore yields more satis- 

 factorily to a comparatively gradual explosive. In the evening 

 we rode back to Mr. Weir's residence at Compaiiia, and on the 

 following day I returned on board the ship, which weighed anchor 

 the same afternoon, and proceeded southward towards Talcahuano. 

 Talcahuano, where we lay from the 4th of September to the 

 4th of October, is the most important seaport in southern Chili, 

 and possesses an excellent and roomy anchorage. It is situated 

 in a fertile and picturesque country ; and it is in direct com- 

 munication by rail, not only with Concepcion and all the more 

 important towns of the south and central provinces, but also by 

 branch line with an extensive grain-producing territory bordering 

 on Araucania, whose produce it receives. Concepcion, which 

 takes rank as the third city in the Republic, is nine miles from 

 Talcahuano, and lies on the bank of the Bio Bio, a broad, shallow, 

 and sluggish river. The houses and public buildings there have 

 the appearance of considerable antiquity, although in reality the 

 greater number must have been rebuilt since the great earthquake 



