Marine and Pocket Chronometers,
Author: H. von Bertele
310 pages + 8 page bibliography, 350 items illustrated
CHRONOMETERS - Marine and pocket chronometers, pocket watches with tourbillons or carousels form, in the large family of clocks, a small group of very precisely running timepieces with little sensivity to external influences, such as variations in temperature.
Since its invention, the marine chronometer has led to greater safety in sea travel. Taking a chronometer along solved the 'longitude problem' - the problem of determining geographical east-west distance on the high seas and thus the precise location of the ship at any time.
In the period from 1785 to about 1900, fine mechanical development dominated the production of chronometers, in order to make them more accurate and less sensitive. Thus there was a remarkable variety of balance wheel designs that were meant not only to compensate for temperature influences in simple terms, but also to eliminate the so-called 'middle' temperature error.
After the period of further development of the mechanical chronometer that began with Ch. E. Guillaume's invention of Invar in the last years of the 19th Century and was typified by progress in metallurgy, chronometers steadily lost their importance, thanks to the invention of wireless telegraphy and electronic timepieces.
For the collector, the realm of chronometers makes different and sometimes more stringent demands than that of household clocks and pocket watches. Because of a lack of suitable literature, it was formerly difficult to familiarize oneself sufficiently with the problems of the chronometer and obtain precise information as to the construction and function of these precision instruments.
In the text, the author takes up the fascinating development and history of the chronometer, portrays the most important manufacturers in short biographies, and reports on the great voyages of discovery in the 18th Century that proved the utility of the chronometer as a navigational instrument. The illustrations section, divided into five sections on the basis of historical and technical standpoints, portrays some 350 chronometers as they are offered as collectors' items in the antique trade and at auctions or seen in private collections, with special emphasis placed on illustrations of their movements.