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An electronic instrument used for measuring extremely short intervals of time, such as the time of passage of a rifle bullet between two points.



an instrument for comparing the readings of two clocks.

The two disks of a chronoscope have narrow, uniformly spaced radial slits: one disk has ten slits numbered from 0 to 9, and the other has 100 slits numbered from 0 to 99. A flash lamp is positioned behind the disks, which rotate on a single axis with angular velocities of 1 and 10 revolutions per second, respectively. The flash lamp fires upon reception of electrical signals from the clocks being compared, illuminating the slits and numbers above the lamp at the given instant. A set of fixed index marks permits the observer to determine readings down to one-tenth of a division of the second disk, which corresponds to a nominal precision of 0.1 millisecond. The difference in the readings of various clocks may be determined with high accuracy by feeding electrical pulses from the clocks to a chronoscope. Photographic chronoscopes are equipped with a device for photographing the disk readings.

Chronoscopes were commonly used in astronomy, physics, and experimental biology until the mid-20th century; they have been replaced by more advanced electronic instruments.

References in periodicals archive ?
In DT, when the character Scudamour is transported through the chronoscope, he discovers that he has a "sting" (63): "It was in his forehead, like a unicorn's horn.
the calibration of the Wheatstone--Hipp chronoscope (see Fig.
the chronoscope (which had the advantage of incorporating a visible
recommendations for its use, concluding that 'the chronoscope, in
fertility" (30-31 in Hooper's text); the insect- or machine-like precision of the Stingingman's method of injecting his victims with venom (35); the insect ingredients within the Othertime meal that Scudamour suspects of maintaining the poison in his horn (80); the disturbing dreams that plague the chronoscope observers after witnessing the scenes in Othertime (33); the "dreams" and "waking hallucination[s]" of Othertimers leading to discoveries of more "historical" versions of the "Smokehorse" and other fabulous creatures from Othertime nursery- and folktales (88); and the nightmares that children suffer so that the Othertime experimenters may exploit them to spy on our Earth-time (88-89).
next to Scudamour's statement (written in the usual ink) that they rarely can see things "ten miles away from the Dark Tower" while viewing Othertime scenes through the chronoscope.
The Scotsman in this fragment has been supervising Lewis's chronicles of the chronoscope adventures, almost reading over his shoulder and commenting all along, and in this case he smirks at Lewis mischievously in stating that Scudamour claimed to have got Lewis reminiscing about war experiences and the books he had written--elements of Lewis-the-author's real past--which have the effect of cheering up Lewis-the-character (who is now narrating).
Considering his lifelong habit of reserve, it's interesting that these self-referential remarks made their way at all into the narrative's initial draft, and curious that memories of The Great War, undoubtedly a traumatic experience, had a soothing effect on Lewis-the-character in the midst of so much degeneracy observed with the chronoscope that had rattled him.
shouted by Scudamour in part IV (also commencing at the top of a fresh page), right as she enters the Stinging chamber and he dashes into the chronoscope.