The present watch is a very good example of the very highly finished pivoted detent chronometer calibre made by Albert H. Potter, who was, and remains perhaps the most celebrated American makers of pocket chronometers. He worked in Geneva where he was able to find excellent craftsmen to help him. This watch incorporates a number of special features peculiar to Potter. There is his patented safety barrel (patent No. 168581) to protect the going train from the effects of mainspring breakage, it uses a considerable amount of height so that the spring is unusually narrow for such a large watch. The pivoted detent escapement has Potter?s own form of pivoted detent with a special arrangement for the passing spring intended to make the passing action as easy as possible, carried on a piece at right angles to the blade near the free-end of the detent, there is a circular counterpoising tail. Banking for the detent is provided by a single pin set in the end of the escape wheel cock, there is, therefore, no adjustment for the depth of locking. The arrangement of the passing spring on an outrigger on the end of the detent was used previously by James Ferguson Cole. The elegant plate design of this caliber, patented on April 5, 1887, allows for easy setting of the train. The winding/setting mechanism, although not patented, is unique for Potter: its intermediate setting wheel moves vertically for engagement, the click pin protruding by the barrel affords an easy and secure means of letting the spring off, and the glazed cuvette, typical for Potter, allows the movement to be viewed. There are minute differences between the early and later Potter chronometers; early ones have spotted movements, the later ones are usually decorated with Geneva stripes and were almost always stamped with Potter's large trademark, whereas the early ones were not. According to Kalish, Potter used to say that he did not have to stamp his cases, because everyone knew his work. The stem in the early ones is held by a screw mounted in the center of the pendant sleeve; in the later, it is flush with the body of the case. The early ones have a traditional balance spring stud, the later ones are more elegant. This watch employs a number of Potter's patents, the details of which are engraved on the bridges. The plate design was patented on January 4, 1876 (American patent No. 8888), the escapement (patent No. 168582), the motor barrel (patent No. 168581) and the balance (patent No. 168583), on October 11, 1875. The same inventions were patented six weeks earlier in England under patent No. 2985 of Aug 25, 1875. Albert Potter's work is not only rare, but always of top quality, offering completely original designs. The energy loss of unlocking his escapement, for example, is less dependant on the state of winding. Consequently, the balance amplitude change is smaller and the degree of isochronism is greater. The unlocking angle is smaller, reducing the risk of setting. Albert H. Potter (1836-1908). Born in Mechanicville, New York, Albert Potter began his three-year apprenticeship in 1852 with Wood & Foley in Albany. He then established himself at 19, John Street and later at 84, Nassau Street, New York. There, in addition to repair work, he made some thirty-five three-quarter plate movements, part with lever and part with detent escapements, cased in gold, which he sold for $225 to $350. In 1861 he went to Cuba where he continued the same kind of work for five years, adding to his designs a quarter repeater and a form of duplex escapement. Back in New York, he took out his first escapement patent in 1868 and soon afterwards moved to the West. He stayed in Minneapolis a short time and possibly in Milwaukee, but by 1870 he settled in Chicago. In 1872, with his brother William Cleveland Potter, he organised the firm Potter Brothers, which was dissolved in 1875, although the business was continued by W.C. Potter until his death. In October 1875, Potter took out patents on compensation balances and improvements in escapements for watches, assigning one half of his rights to John H. Mc Millan of Chicago. The latter may have been in partnership with Potter in his early venture in Switzerland. During his residence in Chicago, Potter designed and built a pocket chronometer which may be considered as his masterpiece. This watch was the prototype from which he made several examples in Geneva, where he obtained his Permis d?Etablissement on February 11, 1876. In an article in the Horological Journal of May 1882, Potter wrote that he invented, made drawings and working models of fourteen different escapements. Among these was also a tourbillon lever escapement which had the escape wheel stationary and the anchor moving around with the cage five times per minute, making the reversals of the momentum too rapid for good performance. Consequently, it was never sold and further examples were never made. As an improvement to that, Potter took a patent in 1886 for an escapement without escape wheel, first invented by Deshay in 1825 and brought out again by Mac Dowell at the London Exhibition of 1855. This patent, with others pertaining to the Charmilles watch, was assigned to the New Haven Watch Company for a reputed fifty thousand dollars. The Charmilles watch was an attempt to produce good timekeeping movements at low prices. Albert H. Potter died on January 25, 1908, 23, rue Tronchin, in Geneva.