Hill, in collaboration with Horace Darwin (of the ever-prolific Darwin family that included the physicist C G Darwin, Frances Galton, and the most famous of all, Horace's father, Charles Darwin, the evolutionist), had invented a mirrored system originally designed to determine the flight paths of aircraft and later used to target German zeppelins for anti-aircraft gunneries.
Hill, sa pakikipagtulungan sa Horace Darwin (ng pa-maani Darwin pamilya na kasama ang pisisista CG Darwin, Frances Galton, at ang pinaka-tanyag na ng lahat, Horace's ama, Charles Darwin, ang mga taong naniniwala sa ebolusyon), had imbento ng isang mirrored sistema ng orihinal na idinisenyo upang matukoy ang flight landas ng mga sasakyang panghimpapawid at mamaya na ginagamit upang ma-target German zeppelins para sa anti-gunneries sasakyang panghimpapawid.