Maker: Patek Philippe
Model: Pendule Carrée
Reference number: 928
Case number: 1540
Year: Circa 1970s
Case size: Approx. 5 1/2 x 5 1/2 x 3 1/2 inches
Case material: Brushed brass
Dial: Black
Movement: Solar cell
Stamps: Case: 1540

The Patek Philippe Reference 928 "Pendule Carrée" is a historically significant solar-powered desk clock, first launched in 1962. It represents an era where Patek Philippe blended 19th-century mechanical movements with mid-20th-century photoelectric technology. 
Features a mechanical Caliber 17'''250 with 18 or 29 jewels. It uses a conventional lever escapement electrically wound by a micro-motor, which is powered by an accumulator charged by the solar cells.
A photoelectric cell (solar panel) mounted on the top of the case provides the power.