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sible. These rods or arcs are at such distances fromeach other, that tiles, without knees, may rest on and hehome by every two ranges, and thus the whole vaultingdepending on the iron may he perfected. The upper partsof the joints are stopped with clay and hair. The underside towards the pavement is first plastered with poundedtiles and lime, and then finished with stucco or fine plas-tering. If the vaulting of hot baths is made double itwill he better, because the moisture of the steam cannotthen affect the timber, hut will he condensed betweenthe two arches. The size of baths must depend on thenumber of persons who frequent them. Their propor-tions are as follow: their width is to he two-thirds oftheir length, exclusive of the space round the bathingvessel (schola labri) and the gutter round it (alveus).The bathing vessel (labrum) should he lighted fromabove, so that the bye standers may not cast any shadowthereon, and thereby obstruct the light. The schola labriought to he spacious, so that those who are waiting fortheir turn may he properly accommodated. The width ofthe alveus between the wall of the lahrum and theparapet must not be less than six feet, so that it may becommodious after the reduction of two feet, which areallotted to the lower step and the cushion. The laconi-cum and sudatories are to adjoin the tepid apartment,and their height to the springing of the curve of thehemisphere is to be equal to their width. An opening isleft in the middle of the dome from which a brazenshield is suspended by chains, capable of being solowered and raised as to regulate the temperature. Itshould be circular, that the intensity of the flame and"heat may be equally diffused from the centre throughout.

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