The Etude magazine, November 1906, p. 703
PRACTICING IN THE DARK BY Maggie W. Ross.
DID you ever suggest to your pupils the plan of practicing in the dark? You would be surprised how much it will help to make sure the fingers, and overcome the bad habit of watching the hand. Because they have no sight and must cultivate the sense of feeling, the blind are peculiarly sensitive in touch. The average piano student can profit by this knowledge, and help himself more than he realizes by a few minutes of nightly practice without the aid of artificial light.
Try going to the piano "when the lights are low" or not at all, and run over the scales in consecutive order. Then play the arpeggios and running chords of the dominant seventh and diminished fifth. Then let yourself go on the pieces you have memorized. You will find yourself musically awakened, for you can hear better when you are not distracted by what you see, and your touch will become more firm and sure and your dependence on printed notes will gradually grow less. Encourage your pupils who persist in bobbing the head up and down in looking from page to key-board to adopt this simple and interesting method of practice. It will help them.