The observation cupola was lowered and raised by means of a hydraulic piston. The searchlight in the cupola possessed a 60 cm diameter lens. It could illuminate objects 3 kilometers away. (It was constructed by Ateliers de la Meuse in Liége.)

A restored searchlight can be seen in the museum of the Fort de Loncin.

Electricity for the searchlight was suplied by a dynamo (type Gramme). The dynamo was powered by a one cylinder steam engine with a small boiler.

Above and below the observation cupola in the Fort de Loncin. (Pictures taken in february 99)

If you compare the picture above with the old drawing on the top of this page you will notice that the main swith (in the drawing bottom left) clearly can be seen (top left in the picture).