This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Test Card. In order to save a certain amount of time, you will find it most convenient to take a piece of cardboard and cut in it an opening the size of the plate you are using, and if possible insert in this opening a piece of blue glass (the effect of this blue glass has been previously explained; it reduces the color scheme of the scene to a monochrome value). By employing this card, even though you do not have the blue colored glass, you will be able to see and readily recognize the proper placement of the various masses to secure the correct effect of composition. The masses will, however, not present their true weight unless you remove their color value, for some of the tints will reproduce in the negative with an entirely different value from what you thought they possessed when you observed them in their natural color state.
252. Up to this point we have tried to impress upon you the importance of careful selection, with the aim of securing a well-composed picture; and, then, to have you satisfy yourself that the relative tones are such as will insure vigor, contrast and the subordination of the more unimportant parts.
Breadths. By the term "breadths" is meant the subduing of what may be called "spottiness," or the scattering of lights and darks. A fine mass of dark trees for instance, unpierced by distracting points of light, will give greater pictorial value than a similar mass of trees finely interspersed with light patches of sky. The reverse of this is also true - a group of figures in light costume should be arranged and massed so that their combined effect is as of one large surface, instead of a scattered series of light spots.