39. Scientific Giant




Short Stories of Science and Invention A Collection of Radio Talks by Charles F. Kettering INDEX		*39.* *Scientific Giant* The principles of quality are shown by having different instruments play the same note. The pitch of course is the same and the loudness is easily controlled. The piano, the violin, the trumpet or the oboe are readily distinguished by their overtones which give them individuality. The mechanism for mixing pure tones of varying pitches and intensities makes the modern electronic organ possible. After Helmholtz had finished his studies on sound, he did work in connection with the mechanism of sight. Often when driving along a road in the dark, we have been startled by the light coming from a cat's eyes. The Egyptians who were cat worshippers attributed this to the animal's mystic power, but Helmholtz thought it was only a reflection. He reasoned that if the eye were capable of reflecting light from the outside, there must be a means of looking into it from the outside. From this theory he developed an instrument which every optician uses today to diagnose your seeing difficulty. You have all seen the small mirror with the peephole in the center with which the specialist actually examines the inside of your eye. Helmholtz developed this device in 1850 - nearly a hundred years ago, but it was just the beginning of his research on vision. He discovered and named the fault known as astigmatism and studied the muscles and actions of the eye and devised lenses to correct this fault. His book on PHYSIOLOGICAL OPTICS contains the results of all of these experiments and stands today as one of the most important works ever written on the subject.