in a dry cellar for nine months the barrels were opened. It was found that the hair had been almost entirely eaten away by the action of the lime, and the mortar consequently broke up and crumbled quite easily. The mortar containing the Manila hemp, on the other hand, showed great cohesion, and required some effort to pull it apart, the hemp fiber being undamaged. Sand/aggregate For fine plasterer's sand-work, special sands are used, such as silver sand, which is used when a light color and fine texture are required. In the United Kingdom this fine white sand is procured chiefly from Leighton Buzzard; also in the UK many traditional plasters had crushed chalk as the aggregate, this made a very flexible plaster suitable for timber-frame buildings. For external work Portland cement is the best material on account of its strength, durability, and weather resisting external properties, but not on historic structures that are required to flex and breathe; for this, lime without cement is used. Sawdust has been used as a substitute for hair and also instead of sand as an aggregate. Sawdust will enable mortar to stand the effects of frost and rough weather. It is useful sometimes for heavy cornices and similar work, as it renders the material light and strong. The sawdust should be used dry. The sawdust is used to bind the mix sometimes to make it go further. Methods The first coat or rendering is from 1/2 to 3/4 inches thick, and is mixed in the proportions of from one part of cement to two of sand to one part to five of sand. The finishing or setting coat is about 3/16 inches thick, and is worked with a hand float on the surface of the rendering, which must first be well wetted. External plastering Stucco is a term loosely applied to nearly all kinds of external plastering, whether composed of lime or of cement. At the present time it has fallen into disfavor, but in the early part of the 19th century a great deal of this work was done. Cement has largely superseded lime for this work. The principal varieties of stucco are common, rough, trowelled and bastard. . Common stucco for external work is usually composed of one part hydraulic lime and three parts sand. The wall should be sufficiently rough to form a key and well wetted to prevent the