Patek Philippe. A rare early steel wristwatch of small size with independent seconds

Patek Philippe. A rare early steel wristwatch of small size with independent seconds
Signed Patek Philippe, model Calatrava, case no. 612301, movement no. 180810, 1910s
The nickel plated movement jewelled to the centre with 19 jewels, bimetallic balance with micrometer regulation, adjusted to heat, cold, isochronism and to five positions, with Geneva quality seal, the two tone brushed steel dial with Roman quarter hour marks and baton five minute divisions, outer seconds ring calibrated in fifths of a second, blued steel hands and sweep centre seconds, in circular case with flat bezel and snap on back, case, dial and movement signed
30 mm. diam.