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.
The student should test all this work in Statics by drawing figures very carefully and on a large scale, in accordance with the general instructions as described in the sections, and should purposely make some variation in the relative positions and amounts of the forces from those indicated by the figures. By this means the student will be able to obtain a virtual demonstration of the accuracy of the laws of Statics as formulated. The student should also remember that the laws are theoretically perfect; and when it is stated, for example, that certain lines should be parallel, or that a certain line drawn in a certain way should intersect some certain point, the mathematical laws involved are perfect; and if the drawing does not result in the expected way, it either proves that a blunder has been made, or it may mean that the general method is correct, but that the drawing is more or less inaccurate.