Anti-Gravity Device

These devices, often called 'AGDs', were comparatively portable (as they could be placed on flying boats). They played a major part in the later World Wars, but were lost long before current times.

[The Anti-Gravity Devices] are spheres which can have a certain amount of mass input. A field will expand from the sphere until that quantity of mass is encompassed and within that field the gravitational force is modified by some amount anywhere from 0.01-0.99 times the amount of original force.

A short description salvaged from a child's school notes, presumably from a field trip to an AGD factory