Weekly Photo Challenge: Illumination
The photo was taken in December 2012. I was joining the conference at Te Papa Museum, Wellington and this ball (looks like) is a mascot. Children (and me) love to roll the ball, wet our hands.
I got this data from the website: it is 1.4 billion years old gabbro stone (a coarse crystalline basalt often called Swedish Ebony Granite) from Transvaal, South Africa and sits on a base stone of Indian Hassan Green Granite. The weight is 0.79 tonnes and 82 cm diameters. It is using low pressure water from 500-litre tank to rotate the ball. The layer of water between ball and base is just 0.2 millimetres thick. Solenoid-controlled jets pulse the water to keep the ball moving when no one is pushing it.For hygiene reasons, the water is treated with swimming-pool chemicals and changed weekly