Barnette's Breathing Exercise
While the drawing above is not in Barnette's book (it is from Gray's Anatomy), it does illustrate nicely the part of the body that concerns this post.
I include the following passage from Barnette’s book (it is on page 11 in the link in the first line of this post) since the exercise found there is one that was taught to me by Margaret Harshaw, a musical descendant of the great Garcías. She called it “The Walking Exercise.” Barnette's book is the only place where I have found it in black and white.
The one exercise that I give, when I deem any necessary, is: Stand squarely on both feet with your arms hanging loosely at your sides, your fingers clasping gently the folds of your dress that lie against them; then shut your teeth almost together, and through the small aperture that is left, suck in the air steadily with a little noise,— imagine your body to be an empty cask, into which you arc pouring water or air, in a small stream, that will touch the bottom first,— then slowly fill up the body—vessel—to the brim, (be careful not to move, voluntarily, a single muscle; do not think about abdominal, or lateral, or transverse pressure, or muscles or anything except of filling your cask as full and as slowly as possible); then, when your lungs are comfortably full of air, draw in the pit of the stomach, as if about to ejaculate a deep, prolonged o - - - - - h! (try the experiment of the oh, two or three times) then shut your mouth and walk slowly across the room; when you reach the other side, turn around, relax every muscle and let your breath exhale quickly. Do this at four different times during the day; also at night, after you are in bed, lie on your back, with your arms at your side, inhale your breath slowly, through a nearly closed mouth, then exhale just as slowly; do this four times, with intervals of a few minutes between. When you once become accustomed to the sensation of well filled lungs, you will take sufficient breath for every need, as instinctively and unconsciously as a bird or a babe.
—Annie M. R. Barnette, Talks about Singing: or How to Practice, 1896, page 11. Find this text on the Members download page.