The bowling balls
10 November 1972: CERN’s Bent Stumpe places an order for 12 bowling balls for a total cost of 95 US dollars. Although not evident at first sight, he is buying the heart of some of the first tracking devices to be used in the SPS control room. Today, Bent Stumpe’s device would be called a desktop mouse…
The first order for 4 bowling balls later changed to 12 balls. The bowling balls became the heart of Bent Stumpe's mouse.
The heart of the device was the ball that the user would move his hand over, while the cursor followed the corresponding movements on the screen. “We needed very round, well balanced and smoothly moving balls and we thought that bowling balls best met these requirements”, recollects Bent Stumpe. "The SPS control room needed three such devices, plus a prototype, and so an order was placed for four bowling balls. As the firm only wanted to sell a minimum of 12 balls, the order was changed accordingly. This led to discussions with the purchasing office, which required an explanation for such an unusual material request."

This tracker ball was among CERN's first tracking devices. The bowling ball is clearly visible. (Picture 1)
The first mice that industry developed and commercialized in the 1980s, years after these first developments at CERN, were based on the same optical principle as the one designed by Bent. However, they were much smaller because everything was miniaturized compared to the original CERN design. “Our device was very big and the box that contained all the mechanics and electronics was installed under the console so that the user could only see the ball”, he explains.

Another CERN tracker ball possibly older than Bent Stumpe's. If you happen to know who made it, please contact us! (Picture 2)
The inner workings of Bent Stumpe’s tracking device The x-y movements of the ball are transmitted to two bearings (one for each direction), which then transmit them to the incremental encoders. The encoders and the rest of the electronics then send a stream of digital signals to the computer telling it the direction and the speed of the movement. |