Mid-Century nickel-plated desk lamp, ca 1950.
The lamp is called tumbler, in Dutch it is called tuimelaar/duikelaar.
The shade can be adjusted into different positions, as the counterweight of the ball keeps the lamp in balance. The lamp rests on a separate metal ring-shaped holder.
Manufactured by Daalderop, The Netherlands.
Diameter shade 14 cm
Height 40 cm