The limitations of the stop watch as a precision instrument

IN MANY scientific and engineering measurements the quantity, time, is an important factor. Its value may be required within widely varying limits of accuracy. A high degree of precision can of course be obtained with our present-day astronomical clocks in proper environment and their usefulness greatly extended by electrically relayed circuits. This method, however, is cumbersome, leaves much to be desired and is not generally applicable to laboratory measurements, not to mention the wide variety of field work. The result is, the more convenient stop watch is frequently the criterion used in judging intervals of from a few seconds to periods between appointments with the dentist.