Timing Contest of 1931: S6.52 - Restart period+ 0.06 - Error of compensation per degree C+/- 0.033 S?2.08 Patek Philippe began its tourbillon production in the 1860s. The earliest recorded Patek Philippe tourbillon, No. 25298, was made in 1864. Since then the company has made around 100 tourbillon regulators. Almost all were made for the observatory timing contests. Most were retained by Patek Philippe and entered in various timing contests, which explains why there are only around a dozen of them known in private hands. They were predominantly entered in the Geneva Observatory contest, however some were presented at the Royal Kew Observatory contest. These watches revolutionized Observatory competitions. As the present watch testifies, they are superb machines: exquisitely finished with extreme attention to detail. The regulator pins are micrometrically adjusted to maximize isochronism, the wheel train is gold, the carriage is perfectly poised, the escapement is undercut to make it as light as possible so as to improve the safety of the drop and to decrease resistance during unlocking. Even the click for the mainspring?s ratchet wheel was made double as a safety measure. The largest Patek Philippe tourbillons are 24 lines (55 mm). Only two are known to have been made (198276 and 198400). The next are 22 lines, as is this watch. Only two of these (197585, 197672) have appeared at auction, one of which was in a later case. The first series of 22 line tourbillons appears to have consisted of four watches (197669 - 197672). One of them, No. 197670, retained by the company, is shown in ?Patek Philippe, Geneve? by Martin Huber and Alan Banbery, Germany 1993, fig. 144. The present watch is unique in the sense that it is in exceptional condition and is the most complete Patek Philippe tourbillon ever offered at auction. It is accompanied by its original case, as well as the antimagnetic observatory contest display case and the original silver sector contest dial.