Marine chronometer

About: Marine chronometer is a research topic. Over the lifetime, 116 publications have been published within this topic receiving 633 citations.

The Place of Astronomy in Navigation

Abstract: Of the 293 papers published in the Journal, eighty-two, or 28 per cent, have been concerned with astronomical navigation This, however, gives a false impression of its present-day importance There was a time when conventional astronomical navigation provided the only means of determining position, in the absence of recognizable landmarks; and it still provides the only fundamental method independent of man-controlled devices But there has been no change in principle since accurate time became available through the combination of radio time-signals and chronometers The papers have dealt with techniques only The large number is evidence of the abiding interest in astronomical navigation; but it also indicates the realization that, while the principles of astronomical navigation are unchanged, the conditions of its application have undergone radical change Techniques have had to be improved under the pressure of necessity, so that the practice of astronomical navigation is now simpler than it has ever been

Tables Requisite to Be Used With the Nautical Ephemeris, for Finding the Latitude and Longitude at Sea: Published by Order of the Commissioners of Longitude

Abstract: Successful long-distance navigation depends on knowing latitude and longitude, and the determination of longitude depends on knowing the exact time at some fixed point on the earth's surface. Since Newton it had been hoped that a method based on accurate prediction of the moon's orbit would give such a time. Building on the work of Euler, Thomas Mayer and others, the astronomer and mathematician Nevil Maskelyne (1732–1811) was able to devise such a method and yearly publication of the Nautical Almanac and Astronomical Ephemeris placed it in the hands of every ship's captain. First published in 1767 and reissued here in the revised third edition of 1802, the present work provided the necessary tables and instructions. The development of rugged and accurate chronometers eventually displaced Maskelyne's method, but navigators continued to make use of it for many decades. This edition of the tables notably formed part of the library of the Beagle on Darwin's famous voyage.

An accurate synchronizing chronometer

Abstract: This article describes a timing system, based on a mechanical chronometer with a synchronous display, which allows determination of time-dependent functions without incurring the errors inherent in personal observation. The chronometer can be driven by most types of time source, and the device has a wide range of application.

Radio chronometer calibrating device

Abstract: PROBLEM TO BE SOLVED: To solve the problem with radio chronometers, which undergo calibration of time indication with reference to a standard radio wave, that the standard wave is difficult to receive in buildings, basements and steel-framed ferroconcrete condominiums on account of the insufficient field strength of the wave and that, if calibration with reference to the standard radio wave is unsuccessful, such a chronometer will operate as a quartz chronometer but only with errors of about 15 seconds per month, such errors accumulating over time to make accurate time indication impossible.SOLUTION: In each of transmitters 110 and 100 for radio chronometers, a single-chip microcomputer 11 in the transmitter acquires date and time-of-the-day data based on chronometer data in a PC 200 calibrated according to Internet time information and initializes a microcomputer chronometer in the single-chip microcomputer; and on the basis of the initialized microcomputer chronometer, a digital-to-analog converter (DAC) 12 modulates the JJY standard radio wave and emits from a band pass filter 13 and a power amplifier 14 or from a short antenna 15 a weak radio wave in conformity with the standard radio wave.