It is necessary to provide for carrying off the rainwater and snow from the roofs, to prevent them from running over the face of the building, and in many cases to collect them for storage and use.

This is effected by gutters of different forms leading to vertical rain-water pipes, which latter conduct the water to drains provided for it. Some of the principal forms of iron and lead gutters are described in Chap. XIV. under the head of Plumbers' Work.

Wooden gutters are sometimes used in the country, or for very temporary buildings. They consist merely of Y-shaped or rectangular channels made of boards nailed together, and require no further description.

Queen-post Hoofs are not included in the Elementary Course, but Figs. 326 to 328 from Part II. are inserted here in order to give a general idea of its form and construction, and to make the table of scantlings more useful.