154 Mr Hamilton's Observations on recent Earthquakes 



geological facts relative to Tacna and the surrounding country. Tacna, 

 an Indian town of some antiquity, and now the capital of the province of 

 the same name, is situated about 13 degrees south latitude, and stands 

 in the desert, about midway between the mountains and the sea. It is 

 NE., and forty miles from the sea-port town of Arica. The desert at 

 this part of the coast is about fifty miles wide between the Andes and 

 the sea, so that Tacna is twenty-five miles from the Pacific Ocean, and as 

 has been ascertained by the barometer, is elevated 1400 feet above it ; 

 the desert there from the sea to the mountains is an inclined plain. 



It may be said that there is no rain at Tacna, though at night, during 

 •winter, i. e. June, July, and August, there are some drizzling showers, or 

 what we may call Scotch mist. The place is supplied with water for all 

 purposes by a stream which issues from a ravine on the Andes; no part 

 of tliis stream reaches the sea ; the irrigation of the cultivated ground 

 about Tacna takes so much of the water, the remainder is evaporated or 

 absorbed by the desert. 



The climate of Tacna is delightful, the mean annual temperature is 

 about 04° Fahrenheit; the proximity of the snow-capped Andes on the 

 one hand, and the ocean and trade- wind on the other, is the cause of the 

 moderate heat. 



The mountain of Tacora is due east from Tacna, its summit is a trun- 

 cated cone, and appears to be of volcanic formation ; it is covered with 

 snow, and elevated lf),000 feet above the ocean. 



The city of Tacna consists of three streets, which are about a mile 

 long, and parallel to one another; they arc crossed at right angles by six 

 or seven other streets, thus dividing the town into a number of parallelo- 

 grams, — at the lower extremity of the town, that nearest the sea, the 

 cathedral, a large edifice, is, or rather was, to be seen. Prior to the 

 earthquake of 1833, the best houses were built with adovies, i. e. very* 

 large flat bricks, merely dried in the sun ; a house so constructed is well 

 adapted to withstand an ordinary earthquake. About fifteen miles above 

 the town, and half a mile from the bank of the river, there is a copious 

 spring of hot sulphureous water; its temperature is 9(3 : Fahrenheit. The 

 country in the vicinity of Tacna seems to be of volcanic origin, trachyte 

 abounding in the district, — at some parts of the desert between Tacna 

 and Arica a hollow sound is produced by the tread of a horse or mule. 

 At Santa Rosa de Chaca, a short distance south of Arica, grey copper-ore 

 is found in abundance, and in the Quebrada de Achi pyritical copper-ore 

 is obtained. 



I very briefly notice some of the other places which were affected by 

 the earthquakes of 1831-3, it may illustrate the power of the agent which 

 operates in such an astounding manner as we have experienced in these 

 convulsions. Across the Andes, 300 miles from Arica, is the city of La 

 Paz, about 150 miles from it towards the south is the city of Oruro, and 

 seventy miles east from it, and in about the same latitude, is the large 

 city of Cochabamba • 200 miles from Oruro, in a SE. direction, is the fa- 



