26 NOVEMBER 1910, Page 16

[To THZ EDITOR 07 THE "SPECTATOR."]

Sra,—Aluminium has sunk to about 11d, a pound, a fourth of the cost of copper in bulk or in sheets. Roofs may be made of sheets passing from cave over the ridge to eave, and saving half the cost of roofing, with less weight and less danger of fire. Tar with a tenth of sulphuric acid makes a strong lacquer to make floor-boards proof against damp and