Split seconds that are ages to a bullet or camera shutter are measured as easily as a wrist watch measures the time of day by a new device called the chronoscope, developed by the research division of Remington Arms Company. The device, built into a small pona:?;v\mfin’el_splits the second 1,000 ways, and will measure from one up to 200 milliseconds with less than one percent of error. It already has proved its value in studying the effect of velocity and flight of time of bullets on accuracy, range, trajectory and hitting power, but its use is not confined to ballistics. Many of the important operations in science and industry performed in less time than is needed for the flick of an eyelash can be clocked by the chronoscope. The measurement of a time interval is indicated from the quantity of electricity which passes through a galvanometer while the measured event is occurring. A vacuum tube switching circuit starts the current at the beginning of an interval and stops it at the end. A photo-electric cell can be used to obtain start and stop impulses. A single scale from which readings are taken actually serves as five scales. The selection is made with a switch which converts scale to one of five time ranges. Ranges are 10, 20, 50, 100 and 200 milliseconds. The chronoscope can be used in any location, since the filaments of the tubes can be energized with batteries where 110-volt alternating current is not available.