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lower ends of the two upright pipes enter into the top ofthe tub, and under each pipe is a kind of small stoolwhich the water falls on. The water loaded with air,dashing against the stool with great velocity, rebounds,and its air is disengaged : a pipe communicating with thetop of the tub carries the air to the furnace, while thewater runs out at a hole in the lower part; a sufficientheight of water being kept in the tub, above this hole, toprevent any air from escaping by it.

III. A funnel and pipe ’without air holes , inserted into an

air vef 'el.

M. Mariotte, in his treatise du mouvement des eaux ,gives an account of another contrivance for blowing fireby a fall of water, which Belidor fays, from the infor-mation of a friend who travelled in Italy, is used in theTiburtine mountain near Rome, and near Salan on thelac de Guarde.

A wooden or tin pipe, fourteen or fifteen feet high,and one foot in diameter, has its lower end fixed into anair vessel or inverted tub, as in the preceding article, fromone fide of which a blast-pipe goes tapering to thefurnace.

The upper end of the large upright pipe is contractedto an aperture of three or four inches, into which is fitteda funnel, whose neck exactly fills it. Into the funnelthere falls a stream of water, from the height of ten, fif-teen, or twenty feet; which we may presume to be dashedinto drops in its fall, and to push down air before it onthe fame principle as in the machine of Tivoli alreadymentioned.

This