Ernest Guinand (c1810-1879) was an important master watchmaker from Le Locle, who, together with the famous Auguste Grether, specialized in the production of tourbillon carriages.
According to the records of the Neuchâtel Observatory, Guinand's first tourbillons were made between 1865 and 1867. Many of them were tested at the Observatory, amongst which two were awarded the second and third prizes in the 1879 contest, Category C for pocket chronometers featuring bascule (lever) escapements.
Although his carriages were often not signed, they are easily identified by their distinctive A-shaped frames (see Reinhard Meis Das Tourbillon, p. 43, Z45 "Guinand 2"). They were mostly fitted with pivoted detent escapements, such as the present watch, some with lever escapements.
Guinand supplied his tourbillons to renowned watchmakers such as Girard-Perregaux and Montandon but was supposedly also commissioned by Patek Philippe with the design of their first tourbillon regulator in 1864.
Two other pocket chronometers with tourbillon regulator made by Guinand with the bridges in the form of his initials are known to exist: no. 3321, made for the Spanish market and fitted with a lever escapement, sold in this saleroom on 18 May 2004, lot 318. The second example, unsigned and with unknown number, also with pivoted detent escapement and presumably also for the American market, was sold at public auction in 1995.
James Emmett Caldwell (1813-1881) began his career as an apprentice to a silversmith in Philadelphia. In the early 1830s, he opened his own watch and jewellery shop which became known as J.E. Caldwell & Company in 1848. The company retailed watches made by the most celebrated manufacturers, notably Ekegren and Patek Philippe.