The huge flocks of sheep, varying in size from 12,000 to 80,000, are mostly owned by New Zealand ranchers who have settled in Argentina in recent years. They are shepherded on the open pampas by gauchos on horseback, whose chief duty is to keep the flocks apart, and so prevent confusion of ownership or the spread of contagious diseases. Formerly the mutton was burnt as fuel, only the wool, tallow, and skins being sold; but since the advent of cold storage it has been exported. The wool is not washed before sale, and therefore fetches a low price. The shearing, which used to be done by hand, is now nearly all done by machinery. Travelling from ranch to ranch each shearer deals, on the average, with about a hundred sheep a day. There is one farm where a flock of about 13,000 Lincoln ewes are milked in dairies, and a considerable profit made. The milk is made into cheese, which finds a ready sale. It is only in exceptionally rich pastures that this is done, and the utmost care is taken that the lamb does not suffer from the deprivation. One of the most important changes of recent years has been the introduction of windmills for pumping water. In the absence of rivers and lakes a well worked by hand was used in the old days to draw water for the house, while the cattle would drink at the shallow lagunas in the hollows of the plain. But as the best land is higher up wells and troughs had to be made. First there was the "jaguel," worked by a horse and rider. Next came an arrangement of buckets on an endless chain, which brought up water and emptied it into the troughs or reservoirs. This was the "noria," and was worked by a horse or mule. But when the water level began to fall--some say through the introduction of alfalfa--and the lagunas to dry up, it was found necessary to dig deeper wells, and to adopt the use of semi-artesian wells. The water, which often is saline, is specially so when drawn from these semi-artesian wells.