Notes And Dimensions. In studying plans, it is important that every reference and explanatory note should be read and carefully considered; every line should be followed its entire length, as what may seem to be of little importance may be the key to a knotty question. In using plans, the workman should invariably follow the figures or dimensions given, and not depend upon scaling, because a mistake may have been made in the drawing, or a change made after the drawing was finished. In such cases the draftsman would not change the drawing, but would simply alter the figures, knowing that the workman will follow the figures instead of scaling the drawing. If drawings are properly made, every essential dimension is plainly noted.

Instead of using the words feet and inches, or their abbreviations, ft. and in., it is the usual custom to make the symbol (') for feet and (") for inches; therefore, instead of writing 6 ft. 9 1/2 in., it would generally be expressed, 6' 91/2"..