Old Zenith chronomete
what is this printing in dial between centre and small cecond?...
It stands for 40-T, one of Zenith's Observatory Chronometer movements...
It could find out the following: The Cal. 40-T is a 12" hand wound movement (thanks blomman for the pointer!) beating with 18.000 bph, produced between 1947 and 1963 in a quantity of 162.000 pieces. There were standard and chronometer-certified movements....
A comparative pic between a chronometer-certified and a standard T-40...
which I found on the web: (left, non-chronometer; right, chronometer version) Note the difference in finishing as well as in the balance wheel and the hairspring stud. Furthermore, the chronometer version is individually numbered also on the barrel bridge...