in diminishing the Quantity/ of Water in Rivers. 103 



•fame gradually more productive, and finally was as copious as 

 ever. 



The metalliferous mountain of Marmato is situated in the 

 province of Popayan in the midst of immense forests. The 

 stream of water upon which the stampers are placed is formed 

 by the union of many small brooks which take their rise on the 

 plateau of San Jorge. The whole environs of the establish- 

 ment are thickly studded with wood. In the year 1826, when 

 I for the first time visited these mines, Marmato consisted of 

 some miserable huts possessed by a few negro slaves. In 1830, 

 the epoch at which I quitted this locality, Marmato exhibited 

 the most exhilarating appearance. There were now seen great 

 work-shops, a foundry for gold, and powerful machines for the 

 division and anialgamati'jn of this precious metal. There was 

 now a free population of nearly 3000 inhabitants settled on the 

 mountain side. All this implies that the wood had been exten- 

 sively cut down for the manufacture of the machines, the con- 

 struction of the buildings, and the preparing of charcoal. That 

 it might be the more easily carried, all this was done upon the 

 plateau of San Jorge itself. The clearing had been going on 

 for scarcely two years, when it was noticed that the quantity of 

 water which was required for the machines had conspicuously 

 diminished. The volume of water is in fact measured by the 

 work which the machines perform ; and trials by gaging at 

 different times have likewise proved the diminution of the 

 water. But this is at Marmato an all-important subject, for 

 a diminution of the fluid moving power is always followed by 

 a diminution in the production of gold. 



In these two cases, of Marmato and Ascension, it is not at 

 all probable that an extent of clearing so local and limited could 

 have such an effect upon the meteorological condition of the 

 atmosphere, as in any degree to vary the annual amount of the 

 rain which falls throughout the country. But the question need 

 not be left in this uncertainty. At Marmato, as soon as the 

 diminution of the supply ,of water was ascertained, a rain-gauge 

 was established ; and it was found, by the observation of tlie 

 second year, that a greater quantity of rain had fallen than 

 (hiring the first, although the clearing had been continued, 

 and there wa.s no af)prcciable increase of the quantity of water 



