When the last of the plastering has been completed the concreting of the cellar should be begun so that it may be drying out with the plastering. For this the best cement must be used, mixed in the proportion of one shovelful of cement to three of sand well mixed, and to this added five shovelfuls of screened pebbles or broken stone, this should be at once spread upon the floor and puddled and trowelled to a perfectly level surface, the whole topped, when hard enough, with one-half inch of fat Portland cement mortar