With Patek Philippe Extract from the Archives confirming production of the present watch with enamel dial and independent second hand in 1902 and its subsequent sale on 31 July 1912.
Patek Philippe's independent dead centre seconds watches are exceedingly rare, only around 60 examples of this predecessor of the chronograph were ever made, both with and without subsidiary seconds.
The independent dead seconds mechanism requires two going trains, one for the movement and one for the sweep centre seconds hand, allowing it to be stopped without stopping the main train in order not to interfere with the accuracy of timekeeping. The invention of this mechanism is attributed to Moise Pouzait, Geneva 1776.
Adrien Philippe's independent dead seconds mechanism (Swiss patent No. 1017 of 23 May 1889, illustrated and described in Patek Philippe by Martin Huber & Alan Banbery, p. 53) varies completely from Pouzait's design. Moving the seconds train over the center bridge created more space, thus allowing a larger balance resulting in better timekeeping.
Roberto Pietro Kohlschitter was born in Monza in 1866. He was hired by the "Ufficio Idrografico" - the Italian Hydrographic Institute - in December 1885. In 1910 Kohlschitter received a silver medal for his "services to nautical sciences". He was still working in 1923. It is not known if Roberto was in any way related to the manufacturer of chronometers and precision instruments in Milan, Giuseppe Kohlschitter.
A similar example is illustrated in Patek Philippe Museum - Patek Philippe Watches Volume I, p. 243, p. 264.