The Tele-Time Viewer was an invention of Gyro Gearloose.
Perfected by Gyro Gearloose in 1975, the Tele-Time Viewer was a large television-like device with which he could watch any event in History he pleased. Over a length of time, Gyro used it to become the first man to decipher a form of prehistoric hieroglyphics used by caveman around 214,200 B.C.E.
Asked by Moby Duck to investigate the creation of a stone tablet written in these hieroglyphs, which the mariner had fished right out of the ocean where it had lain for over two hundred thousand years, Gyro used the T.T.V. to witness the bargaining between Muk-duk and Beegul for ownership of all of the planet Earth's water.
When modern-day Beagle Boys then reclaimed the tablet (the deed to all the world's water), Gyro cannibalized the T.T.V. for parts building a new time machine, which, still built along the same principles as the T.T.V., worked by turning the time-travelers into electrons and then catapulting them backwards in time through the Time Channel.
Behind the scenes
The Tele-Time Viewer appears in (and is destroyed during the events of) the 1975 comic story The Deep Sea Deed.