This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Outside of its general educational value freehand drawing is as abso-lutely essential to the trained architect as it is to the professional painter. It is obviously necessary for the representation of all except the most geometric forms of ornament, and it is equally important in making any kind of a rapid sketch, either of a whole building or a detail, whether from nature or in the study of plans and elevations. It is perhaps not so generally understood that the training it gives in seeing and recording forms accurately, cultivates not only the feeling for relative proportions and shapes, but, also, that very important architectural faculty-the sense of the third dimension. The essential problem of most drawing is to express length, breadth, and thickness on a surface which has only length and breadth. As the architect works out on paper, which has only length and breadth, his designs for buildings which are to have length, breadth, and thickness, he is obliged to visualize; to see with the mind's eye the thickness of his forms. He must always keep in mind what the actual appearance will be. The study of freehand drawing from solid forms in teaching the representation on paper of their appearance, stimulates in the draughtsman his power of creating a mental vision of any solid. That is, drawing from solids educates that faculty by means of which an architect is able to imagine, before it is erected, the appearance of his building.