On this day in 1887 Dr. Graham Edgar, developer of the octane rating system, was born in Fayetteville, Arkansas. During the pioneering era of the early automobile it was impossible to tell if a gasoline would cause engine knocking due to irregular combustion. This was caused by non standard refining processes and the use of numerous types of fuels. The only way to find out if a fuel would work in your car was to fill it up and give it a shot. 1926 while working for a division of General Motors and Standard Oil known as Ethyl Gasoline Corporation Edgar solved this issue by developing the octane rating system. He found that isooctane would not knock in any engine under any operating conditions, while n-heptane would always knock in any engine. By mixing isooctane and n-heptane in different amounts, he obtained fuels of all qualities, the percentage of isooctane in the mixture being the octane number.