The celatone was a device invented by Galileo Galilei to observe Jupiter's moons with the purpose of finding longitude on Earth. It took the form of a piece of headgear with a telescope taking the place of an eyehole.
![](http://upload.luquay.com/wikipedia/commons/thumb/8/83/Celatone_%28ricostruzione%29_IF_102793.jpg/220px-Celatone_%28ricostruzione%29_IF_102793.jpg)
![](http://upload.luquay.com/wikipedia/commons/thumb/f/fd/Celatone01.jpg/220px-Celatone01.jpg)
Modern versions
editIn 2013, Matthew Dockrey created a replica celatone, using notes from a version created by Samuel Parlour. From April 2014 to January 2015, Dockrey's celatone was on display in the Royal Observatory, Greenwich in east London.