Windmill, is a contrivance for grinding corn, or raising water: it is put in motion by the action of the wind upon its sails, or vanes.

In the 55th vol. of the "Gentle-man's Magazine" for 1785, we meet with an account of a windmill for raising water, by Mr. MERRiman. It is furnished with a large sail, affixed to a mast, that inclines to the horizon, and thus imparts motion to certain pieces of machinery termed braces, which are connected with forcers ; so that every ga!e of wind will aft on the apparatus, and raise a greater or quantity of water. During tempests, the mast will bend, and the sail yield to their force; so that, when their violence is abated, the upper pacts are restored to their ori-ginal position, without injuring the works. - The mechanical description of such contrivance being foreign toour plan, the inquisitive reader will consult the work above citied.

As windmills essentially contribute to agricultural and domestic convenience, we shall present our readers with a delineation of a spe-cimen of those employed in the vi-cinity of Lisbon ; because the construction of their sails is in some respects different from, and, in the opinion of Lord SomeRvILLE, su-perior to, those used in Britain.

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The advantages of mills, on this construction, are stated by his Lordship to be the following :

1. That the broad part of the sail is at the end of the lever, or branch, and thus an equal resistance may be overcome with less length of branches, or arms. These being consequently shortened, a considerable weight of timber will be rendered unnecessary, and a material saving of expence be obtained, in the height, prime-cost, and subsequent repairs of the mill.

2. The sails, constructed on the plan above represented, may be set to draw in a manner similar to the stay-sails of a ship; and, as they are swelled more than those, in England, Lord S. remarks, that they will render it unnecessary to bring the mill so frequently to the wind; a practice which, in machines of the usual construction, is always attended with considerable trouble.

In November, 1783, a patent was granted to Mr. Benjamin Wiseman, for his invention of sails, with horizontal levers, designed to communicate motion to windmills. His patent is now expired ; but, as a description of such machinery would be unintelligible without the aid of engravings, the reader is referred to the 4th vol. of the " Re pertory of Arts" etc.; where his specification is illustrated by two plates.

A patent was likewise granted in December, 1795, to DaniEL Maunsel, Esq. for his invention of a horizontal windmill, upon new principles, for grinding corn, and for other purposes : an account of his complex machinery is inserted in the 7th vol. of the work above cited, and elucidated with two engravings.