In the dry part of the river the extraction of the sand, stones, and cascalho is done solely by hand.  The men carry the sand upon their heads in small wooden bowls called carumbes, which hold about 15 kilogrammes, and throw it somewhere where the deposit will not interfere with the exploitation.  Almost all of these men are negroes, who run with their load upon their head over the white sand, singing some song of their country.  It, is very picturesque, but it is doubtful whether it is economical.

Since the century and a half that these rivers have been dug and redug, it may be admitted that wherever the cascalho has been easy of access it has been removed; and that wherever it has not been, little attempt has been made to work it.  How have these attempts, which have doubtless been made at several periods, come out?  This would at present be very difficult to ascertain.  The exploitations have been too numerous to allow us now to estimate the value of a bed from the data furnished by geology, and local tradition is too uncertain or exaggerated to allow us to place much confidence in it.

We can, at the very most, say that if some points still remain intact it must be because the exploitation of them was too difficult with the processes that were employed, and this should be a reason, were it desired to attempt new operations, for having recourse to entirely different modes of work.

It would seem rational, as regards this, to try to put to profit the hydraulic power that the flumes and canals render disposable for mechanically extracting the sand.  The field to be worked being naturally long and narrow, it would be the proper thing to employ a series of inclined planes distributed along the banks, actuated by water wheels, and corresponding to so many small working points.  The river often flows through a genuine canon with nearly vertical walls, where space would be absolutely wanting for installing wheels elsewhere than at the exit of the canal, and if may become necessary to distribute the power of these wheels along the works.  In these regions of difficult access and few resources it is necessary to dispense with complicated apparatus, and one might in such a case, it would seem, try electric motors, whose installation would be easy.  An exploitation in accordance with these ideas was begun for the first time in 1883 upon the Ribeirao de Inferno at Portao de Ferro.  We shall describe it.

Once established in the country, the first thing to do is to form roads so as to secure communications with the neighboring villages and forests, and afterward to cut down trees for building houses.  These latter are usually constructed, for these works, of untrimmed wood and mud, with thatched roof.  There were thus constructed at Portao de Ferro a few kilometers of roads, then some houses for the engineers and special workmen, barracks for 200 laborers, stores, kitchens, etc., a forge, and a shop with a lathe and a saw run by a wheel at the side.  It was afterward necessary to repair the old lateral canal which had been dug out of the rock in the times of the Royal Extraction, but which had been torn open for a considerable length.  This necessitated the erection of tight walls of dry stone, grass, and mud, for a length of 200 meters, and with thicknesses of from 6 to 10 meters.