Maltese Star Vacuum Discharge Tube on Stand, c. 1890

This Maltese star tube consists of a hinged metal cross inside a glass bulb which has a negative end (the cathode) and a positive terminal (the anode). When activated the metal cross intercepts the cathode rays travelling towards the anode, thereby casting a shadow on the tube's end. This demonstrates that cathode rays travel in straight lines and can be intercepted by solid objects. The glass bulb stands on a turned blackened wooden base.