Technology: Jobs for the Jiggle

Vibration is usually a dirty word in the space age lexicon. The delicate instruments of missiles, aircraft and spacecraft function best in a smooth environment, and scientists are continually searching for means to eliminate the least little bump. But deliberate vibration has its uses too, and last week, in widely separated laboratories, engineers were putting man-made jiggles to work. Applications:

>A "telephone" for deaf-mutes, developed at Israel Institute of Technology in Haifa, uses a compact set of vibrators to communicate as many as 67 words a minute. The "speaker" taps out his message on a set of switches built into a piano-like keyboard. The "listener," his fingers resting on a duplicate keyboard, feels each key or combination of keys vibrate in response to the speaker's signals. According to the telephone's U.S.-born inventor, Aeronautical Engineer Joseph Hirsch, it is a simple matter to put the letters of the alphabet and actual words into an easily understood code of vibrations. Hirsch began perfecting his phone while working on mechanical vibration problems in U.S. Navy missiles, and he is sure the technique can be put to wider use for remote control of dangerous crop-dusting planes, and in military communication systems, where loud, continuous noise often makes virtual deaf-mutes of tank crews and gun captains by masking the sound of spoken orders.

>A fast-writing pen for oscillographs, developed by Stanford University Electrical Engineer Richard Sweet, uses a vibration hardly as violent as a shiver to write a permanent record of oscilloscope traces that have only been caught in the past by delicate and expensive motion picture film. Spewed through a tiny nozzle, the ink droplets pick up a charge from an electrode attached to an oscilloscope. Then they fall, at the rate of 100,000 a second, between two electrically charged plates and hit a rapidly moving roll of recording paper. Each drop carries an electric charge that mirrors the changing electrical signal being detected by the scope. As each drop passes between the charged plates, the charge it is already carrying causes it to change course and hit the recording paper at the proper spot to leave a permanent record of the oscilloscope's otherwise ephemeral traces.