ABSTRACT
The oblique lengths have been altered. The degree of alteration has been determined by the oblique angle. An oblique angle of 60 ° causes a large distortion and the oblique length is thus altered to 13 the true length. An oblique angle of 30 ° causes less distortion and the oblique length is only altered to 23 the true length. At 45 ° the true length is reduced by half. These alterations need not be rigidly adhered to. The ones illustrated are chosen because they produce a reasonably true to life picture of the block, but a complicated component might have to be drawn with no reduction at all in order to show all the details clearly.
