Judge Yerkes was born in Warminster Township, Bucks Co. on 8 October 1843, and is listed in the Chronicle of the Yerkes Family as #547. He graduated from school in East Hampton, MA in 1862, and after a short period of teaching school, he entered on the study of law in the office of Judge Ross at Doylestown. He was admitted to the bar in 1865. In 1868, he was elected District Attorney. He married his wife Emmeline in 1869. In 1873, he was elected to the State Senate as a Democrat, and he was re-elected in 1876. He was a member of the State Board of Managers of the Centennial Exposition, and was selected for President of the Senate. He drafted laws regulating the courts, and introduced the law creating the Hospital for the Insane at Norristown. He was a delegate to the Democratic National Convention in 1872 and 1880. In the Senate, he presided over the judiciary committees, organizing the Democratic Judicial Conventions for the counties of Bucks and Montgomery. In 1883, having declined a re-election to the Senate, Judge Yerkes was elected President Judge of the Courts of the Seventh Judicial District, and won re-election in 1893. In 1895, he was elected Judge of the Superior Court. In 1903, he was nominated for the third term, but the county had become overwhelmingly Republican and he failed of re-election. So after 20 years service on the bench, he returned to the practice of law. He was a member of the Historical and Colonial societies of Pennsylvania, the Bucks County Historical Society, the Pennsylvania Scotch-Irish and German Societies, the Art Club of Philadelphia, and the Acorn Club of Doylestown. He was Rector's Warden of the St. Paul's Episcopal Church at Doylestown. He and his wife Emma had no children.