E-grāmata: Accurate Clock Pendulums

The Shortt pendulum clock, made in the 1920s, was accurate to within one second per year. To achieve that level of accuracy, a pendulum's length must be constant to one part in 15 million for a whole year. Matthys, who was a senior research engineer for about 35 years, gives us the courage to attempt our own amazing feats in accuracy. He describes simple pendulums, the effects of shape, materials and temperature, the complexities of the suspension spring and pendulum rod, the effects of air and the clock case, and special considerations of electronically-driven pendulums. He includes helpful illustrations and references in each chapter. Annotation ©2004 Book News, Inc., Portland, OR (booknews.com)

The Shortt clock, made in the 1920's 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 pendulum clock's accuracy resides in its pendulum. If the pendulum is accurate, the clock will be accurate. In this book, the author describes many scientific aspects of pendulum design and operation in simple terms with experimental data, and little mathematics. It has been written, looking at all the different parts and aspects of the pendulum in great detail, chapter by chapter, reflecting the degree of attention necessary for making a pendulum run accurately. The topics covered include the dimensional stability of different pendulum materials, good and poor suspension spring designs, the design of mechanical joints and clamps, effect of quartz on accuracy, temperature compensation, air drag of different bob shapes and making s sinusoidal electromagnetic drive. One whole chapter is devoted to simple ways of improving the accuracy of ordinary low-cost pendulum clocks, which have a different construction to the more expensive designs of substantially well-made ones. This book will prove invaluable to anyone who wants to know how to make a more accurate pendulum or pendulum clock.