WORKING DRAWINGS, consist of plans, elevations, and sections of the whole, and all the parts, of an edifice, to as large a scale as may be found convenient; generally in outline, excepting the sectional parts, which are frequently shadowed, or scratched, in order to make them more obvious to the workman, for whose use the drawings are made.
The general plans, elevations, and sections, as they cannot be made to the full size of the object to be executed, should all be figured with numbers of measurement, to show the dimensions of all the parts of the edifice, without obliging the workman to refer to the scale, which is not only very troublesome, but liable to lead to many mistakes detrimental to the work.
The plans, elevations, and sections, of the parts of an edifice, ought to be made to the full size; in which case the figuring of the dimensions becomes unnecessary.
Working drawings may be divided into three classes : distinguished severally as Block Plans, General Drawings, and Detailed Drawings.
Block Plans show no more than the outline of the proposed works or buildings, and their position with reference to surrounding objects; in fact, they point out the site of the buildings, and determine the space to be occupied by them. They are drawn to a small scale, so as to embrace the entire site of the works, and so much of the neighbourhood as may be necessary. They contain every information respecting the present state of the building-ground and its vicinity, and the manner in which it will lie affected by the new work; thus, in most instances, it is necessary to show the proposed method of drainage, lighting, water-supply, &e.; and as this will necessarily depend upon the existing state of things, we must mark out the old drains, gas, and water-mains, and the method of connecting them with the new works. It is well also, on such drawings, to give some idea of the comparative levels of the district.
The General Drawings show the whole extent of the new works, and the arrangement and distribution of the several parts. They consist of plans of the various stories, including those of the foundations, and roofs, and indeed of any part of the building where some peculiar treatment renders explanation necessar% ; aerations of every side. of the build
or of so many sides as present a different appearance; amid sections showing the internal structure and arrangement of the works. On each of these drawings, the dimensions of the whole, and of the various paqs, should be carefully figured; the directions in which the measurement are taken, being figured in dotted lines, and the points from and to which they are measured, being clearly defined by an arrow head, or some such contrivance. So much of the details are shown on these drawings as the scale will allow. Perspec tive drawings or sketches may be added, to give a more general idea of the undertaking.
The Detailed Drawings show such parts of the work as cannot be shown on the general drawings with sufficient clearness and accuracy; and are drawn either of full size, or to such a scale as shall make them clearly intelligible to the workman. Such drawings are required both for the decora tive and constructive parts of the building ; thus are included the capitals and bases of columns, entablatures. cornices, tracery, or any other enrichment ; as also the sections of mouldings, string-courses, &e.; and besides these, the method of framing floors, roofs, &c., the patterns of cast-iron or trussed girders, story-posts, and such like, of everything, in short, of which a particular description is necessary. It saves much trouble, if the detailed drawings are made out on separate sheets fur the diGrent trades. These drawings, like the others, should have their dimensions clearly figured upon them, and every drawing should be provided with a scale, from which any further dimensions may be taken by the compasses.
It is usual in drawings, to tint only such parts as are in section ; but it will frequently be found desirable to colour also the parts which stand back, and are in elevation ; and sometimes also to project the shadows, or shade up such parts, so as to give a general idea of their distance from, and relation to each other, as also of their forms, as whether flat, concave, or convex, &c.