Spanish Tidal Flour Mills.

Abstract

Author proposes to give a short description of the construction, working, and efficiency of the tidal flour-mills in use in Andalusia, more especially in the province of Huelva, which are, he believes, little known in England, and which are interesting not only from their extreme simplicity and primitiveness, but also as being perhaps the earliest form of wheel of the turbine class, having come down in their present mode of construction almost unaltered from Moorish times, if not from a still earlier date.These mills are thickly studded all over the '' Marismas," or salt-marshes, which border the lower portions of the Andalusian rivers, within the tidal range. They are built across the " esteros," or creeks, by which these marshes are intersected, at the most suitable points, where the firmest foundation is obtainable, and a sufficient amount of storage available, the natural capacity of the " estero " being increased by means of rough excavations, so as to retain at spring-tides from 500,000 to 1,000,000 cubic feet of tidal water. The total head rarely exceeds 7 feet at springs, and the mill is usually worked until it falls below 3 feet. A spring-tide