Leonard's brain is particularly receptive to particles of raw inspiration; ideas that sleet through the universe and strike inventors' or artists' minds in the dead of the night. As such, Leonard has engineered the gonne and siege engines alongside flying machines, submarines, message encryption/decryption devices, pub game devices, and engines for making very fast coffee. Oddly enough, his creativity seems to stop when needed to give appealing names to his inventions: for example, for his machine capable of travelling submersed in a marine environment he came up with the name of "Going-Under-The-Water-Safely Device".
Leonard was also responsible for painting a picture of the entire Disc, complete with elephants and turtle, on the ceiling of the Temple of Small Gods in Ankh-Morpork. This project was commissioned by Fate as a penance for Leonard's hubris in building the Kite and was meant to be impossible to complete in the ten years allotted so that the Gods would be justified in destroying the city afterwards. Leonard was finished in three weeks.
It is also believed that Leonard was the actual inventor of alternating current, as well as a mechanism for delivering electricity throughout Ankh-Morpork. Unfortunately the name of the device (Divalent Iron Support Structure for the Conducting of High Voltage Alternating Current) was too long to fit into the allocated blocks on the patent form, and the filing was rejected. Leonard was never able to claim recognition for his invention, nor for the Twisted Metal Securing Thingy, the design of which he sketched in the margin of the patent form when trying to come up with a name for it .
The coordinates will take you to one of the more modern Divalent Iron Support Structures, sporting many of those Twisted Metal Securing Thingys. This particular one is located on the Braamfontein Spruit trail, but is easily accessible from the road. Please take care when searching for the cache that you do not give it's hiding place away, and put it back exactly where you found it.