We will suppose our window faces the north, and really a north window should be used, as the light is much more even and nearer the same intensity the whole day.
For convenience sake, we will suppose that we have our subject sitting in the west end of the room and our camera in the east end. To ascertain the proper place to seat your subject, measure a line five feet from the west side of the window toward the center of the room, and then two feet back toward the west from this line. Now place the posing chair at this point. Place the camera about three feet nearer the light than the subject, running backward or forward to get the size head desired. Have the background about three feet in the rear of the subject. Draw the lower opaque curtain on the window all the way up to the top of the lower sash, leaving the top sash open or without any curtain on it. To make a three-quarter view of the face, have the subject, first, to face directly toward the window, and then begin to turn slowly away from the window, until the ear on the shadow side of the face is just barely hidden from view when standing directly behind and looking over the top of the camera. If directions have been followed, the points of light will be seen easily. The highest light being on the forehead just over the left eye, next on the nose, next on the upper lip and the next on the chin, and a soft, delicate halftone on the shadow cheek, with good strong catch lights in the eyes. By catch lights in the eyes I mean the little "dots" of light seen just at the edge of the iris.
At this point notice the shadow side of the face, and if it is difficult to see the detail, or flesh tints, through the shadows, it will be necessary to use the side reflector and reflect a little light into them. Be careful and not overdo it; all that is wanted is to see the detail in the deepest shadows. If the lighting still looks too strong or contrasty, that is, one side is too white and the other too dark, take the head screen of white cloth, and place it just over the head, and between your subject and the open sash or light. This will soften the light very much, and in a greater number of cases the reflector and headscreen will hardly be needed, and should not be used unless they are actually needed. It is hard to say just what length of time to give, as this will depend on the speed of plate used, lens, stop, amount of light on the subject, etc., etc., but it will range from six to twelve seconds. If a full front view of the face is desired, place everything as directed except the camera, and that should be moved away from the light until the subject is on a line with it. If a profile is wanted, follow directions as given, only turn the subject's head away from the light until the profile is secured.