The principle of manufacturing salt from the sea is discussed. An examination of the literature indicates that the only relevant investigation which has been carried out is on the rate of evaporation from large bodies of water. A summary of the relevant methods of assessing the evaporation is made and it is concluded that the aerodynamic approach is the most promising. An approximate equation describing the evaporation from Lake Grassmere as a function of time and brine concentration is derived for average weather conditions. A qualitative discussion on the mechanism of natural evaporation of water from brine ponds by solar energy leads to energy balances which, it is suggested, should be completely investigated to produce an optimum depth of brine in a pond. Material balances are set up for the general case of flow in n ponds. These can not be solved, for the variation of flow with time and a stepwise procedure is adopted to allow calculation of the output of saturated brine under average weather conditions for one, two, more than two, and an infinite number of ponds in a system. The latter calculations are based on what is proved to be an invalid assumption so that the results are erroneous. For the one and two pond cases, an estimate of output of saturated brine under average weather conditions is made and the time required to reach the stage of maximum output assessed.