Showing papers on "Marine chronometer published in 2012"

Evolution of Clock Escapement Mechanisms

Abstract: The paper presents and explains the evolution of details design of the clock escapement mechanisms through the ages. As particularly significant, the following mechanisms are emphasized: the crown wheel (verge & foliot), anchor recoil, deadbeat and detached escapements, and their variations - gravity and chronometer escapements, as well as the English and Swiss lever watch escapements. All important geometrical, kinematical and dynamical properties and the influence of these properties on the clock accuracy are explained.

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.

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.

Chronometer dial and chronometer

Abstract: PROBLEM TO BE SOLVED: To provide a chronometer dial presenting an appearance full of three-dimensional impressions, and a chronometer equipped with this chronometer dial.SOLUTION: A chronometer dial 1 has a microlens layer 11 in which a plurality of microlenses 111 are regularly arranged in a plan view and a decorative layer 12 in which repetitive patterns 121 are provided in similar arrangement to but at a different pitch from the microlenses 111; in a plan view of the chronometer dial 1, the microlens layer 11 and the decorative layer 12 overlap each other; and on the chronometer dial 1, when the centers of microlenses 111 adjoining one another in a plan view of the chronometer dial 1 are linked by straight lines, a plurality of triangles formed by the straight lines are regularly arranged.