An instrument for producing a graphical record of time as shown by a clock or other device. The chronograph produces a double record: the first is made by the associated clock and forms a continuous time scale with significant marks indicating periodic beats of the time keepers; the second is made by some external agency, human or mechanical, and records the occurrence of an event or a series of events. The time interval of such occurrences are read on the time scale made by the clock.

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An instrument for measuring the magnitude of electric current flow.


An instrument for determining either the specific gravity of a liquid or the API gravity.


A scale of temperature measurement in which zero degrees is absolute zero.


The time rate of change of velocity; i.e., the derivative of velocity; with respect to time.


Amount of time an unit, equipment or system is run per hour or per 24 hours.


The specified time interval of a Loran C chain for all stations of the chain to transmit their pulse groups. For each chain a minimum group repetition interval (GRI) is selected of sufficient duration to provide time for each station to transmit its pulse group and additional time between each pulse group so that signals from two or more stations cannot overlap in time anywhere within the coverage area. The GRI is normally stated in terms of tens of microseconds; i.e., the GRI having a duration of 79,900 microseconds is stated as 7900.


Any real function that satisfies a certain equation. In its simplest form, as used in tide and tidal current predictions, it is a quantity that varies as the cosine of an angle that increases uniformly with time


A radarscope phenomenon which appears as a constriction or expansion of the display near the center of the plan position indicator, which can be caused by a nonlinear time base or the sweep plot starting on the radar indicator at the same instant as the transmission of the pulse. The phenomenon is most apparent when in narrow rivers or close to shore.


Fluctuation about a mid-point due to instability, as oscillations of the needle of an instrument about the zero point.


A gravity scale established by the American Petroleum Institute and in general use in the petroleum industry, the unit being called 'the A.P.I. degree' .

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