The inscription “Sistema Brevettato” or “Patented System” on the dial of this watch refers to Swiss patent no. 7197 for a « nouvelle montre 24 heures » (new 24 hour watch), issued on 27 October 1893 to the ingenious watchmaker Charles Couleru-Meuri of La Chaux-de-Fonds.

It indicates the hours from 1 to 24, e.g. diurnal and nocturnal, by means of 12 windows and a rotating disc behind the dial. The disc features two series of numbers, one from 1 to 12, the second from 13 to 24, interposed so that the two series are visible alternately behind the 12 windows of the dial. The disc rotates when the hour hand passes 12.

The case back of this watch is engraved with the Maltese cross which is also reproduced on the mother-of-pearl cartouche on the cover of the wooden presentation box.

The symbol of the Maltese cross is originally associated with the Knights of Malta, who ruled the Maltese islands between 1530 and 1798. Since 1880, it is the trademark of Vacheron Constantin, inspired by a component of the barrel, which had a cross-shape and was used for limiting the tension within the mainspring.

Hausmann & Co.
Hausmann & Co. was founded in Rome in 1794 by Ernst Hausmann, a young German clockmaker and his friend and partner Hermann Frielingsdorf. The firm is still residing in the same premises in Rome's historical centre and represents the world's most prestigious watch and clock manufacturers.