Rating a Chronometer

No chronometer will run for any length of time without variation, consequently its deviation from true time is determined, and allowance made for it by the navigator in his calculations. This variation can be determined in a variety of ways--by comparing the chronometer with the clock of an observatory, by time balls, by transit instrument, and by the employment of the sextant and artificial horizon in a time sight. To determine the rate, find the error made on different days, and divide the aggregate by the specified number of days. The answer will be the daily rate of the chronometer.