USA customers: Passenger flights to USA have been stopped. Airmail gets put in the cargo hold of passenger planes. Hence Airmail to the USA has basically stopped too. Couriers are trying to find altnerative routes. In the mean time please use the FedEx option (FedEx use their own planes and are operating normally).

Drinking Bird - a novel heat engine - £5.99

OUT OF STOCK - click here to be emailed when its back in stock
This is a classic toy. The Drinking bird swings taking regular sips of water until it runs out of water. The toy often runs for days at a time despite just using evaporation of water to power the device. A great demonstration of thermodynamics. More information about the Drinking Bird - a novel heat engine