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Accurate Clock Pendulums

Robert J. Matthys

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
book
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.001.0001
Subject:
Physics, History of Physics

The Shortt clock, made in the 1920s, is the most famous accurate clock pendulum ever known, having an accuracy of one second per year when kept at nearly constant temperature. Almost all of a ... More


Spring suspensions for accurate pendulums

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0015
Subject:
Physics, History of Physics

This chapter deals with the design and performance of various types of spring suspensions for an accurate pendulum clock. It also covers the three basic oscillation modes of a pendulum, the ... More


An electronically driven pendulum

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0032
Subject:
Physics, History of Physics

An electromagnetically driven pendulum is more accurate than a mechanically (escapement) driven pendulum. This is because a pendulum is disturbed less by an electromagnetic drive pulse than by ... More


Effect of the clock case walls on a pendulum

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0031
Subject:
Physics, History of Physics

This chapter describes an experiment designed to determine the effect of the walls of a pendulum clock case on a pendulum. The basic experimental approach was to measure the pendulum's clock rate and ... More


Pendulum air movement: A failed experiment

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0028
Subject:
Physics, History of Physics

A previous experiment showed that the walls of a pendulum clock case can slow down the pendulum via air drag by about 1 second per day. The pendulum has a 2-second period. This chapter describes an ... More


Time error due to air pressure variations

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0030
Subject:
Physics, History of Physics

The rate of a pendulum clock is affected by air pressure. As the air pressure increases, the clock slows down, and vice versa. The basic cause is that the pendulum floats in a sea of air, and when ... More


Dimensional stability of pendulum materials

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0011
Subject:
Physics, History of Physics

The dimensional stability of a pendulum directly affects its accuracy. If the bob sags downward or warps upward, the clock slows down or speeds up. If the temperature compensator shrinks or expands ... More


Putting Q in perspective

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0007
Subject:
Physics, History of Physics

Q is a clock oscillator's quality factor, a measure of how low its energy losses are with respect to the total energy stored in the motion of the oscillator. This chapter ... More


Photoelectronics for pendulums

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0034
Subject:
Physics, History of Physics

Photoelectronics make good sensors for pendulum clocks, because they add no power losses to the pendulum. A swinging pendulum interrupts a light beam, and a light detector provides an electrical ... More


The Allan variance and the rms time error

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0008
Subject:
Physics, History of Physics

The traditional plot of a clock's time error versus time is far superior to the Allan variance for showing a pendulum clock's time performance. The Allan variance is admittedly a universal and ... More


A short history of temperature compensation

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0002
Subject:
Physics, History of Physics

This chapter covers the temperature compensation of pendulum clocks. Temperature compensators can be divided into four groups: mercury for medium expansion pendulum rods (iron), gridiron for medium ... More


Solid one-piece suspension springs

Robert James Matthys

in Accurate Clock Pendulums

Published in print:
2004
Published Online:
January 2010
ISBN:
9780198529712
eISBN:
9780191712791
Item type:
chapter
Publisher:
Oxford University Press
DOI:
10.1093/acprof:oso/9780198529712.003.0018
Subject:
Physics, History of Physics

This chapter discusses how to make solid one-piece type of pendulum suspension springs. There are three types of pendulum suspension springs: the mechanically clamped type, the soldered assembly ... More


Astronomical Time Measurement and Changing Conceptions of Time

Yulia Frumer

in Making Time: Astronomical Time Measurement in Tokugawa Japan

Published in print:
2018
Published Online:
September 2018
ISBN:
9780226516448
eISBN:
9780226524719
Item type:
chapter
Publisher:
University of Chicago Press
DOI:
10.7208/chicago/9780226524719.003.0004
Subject:
History, History of Science, Technology, and Medicine

Chapter 3 explores changes in conceptions of time by examining the work of Tokugawa-period astronomers. It begins in the seventeenth century with the astronomical methods of Shibukawa Shunkai, ... More


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