It's funny you ask that question. Back in 1972 a man by the name of Yakov Rosenbaum worked in Flatbush in Brooklyn to figure that out. What he found was that deltay and deltax were actually Russian spies
BACK IN MY DAY I WALKED TO SCHOOL 15 MILES IN THE SNOW UPHILL BOTH WAYS. AND WE LIKED IT. WHAT WAS I TALKING ABOUT AGAIN? WHO ARE YOU, GET OUT OF MY HOUSE!