An exemption from serv-ing in an office, or performing duties which the law generally requires other citizens to perform. Long v. Converse, 91 U. S. 113, 23 L. Ed. 233; Ex parte Levy, 43 Ark. 54, 51 Am. Rep. 550; Lonas v. State, 3 Heisk. (Tenn.) 306; Douglass v. Stephens, 1 Del. Ch. 476