Eratosthenes was gifted in all the branches of knowledge of his time but failed to top his contemporaries in any one branch. this is the reason , some suppose , that he was nicknamed " Beta " Hewas an outstanding athlete , poet , astronomer , historian , and mathematician , and various of his works are mentioned by later writers. We have already seen , in Problem study 4.3 ( c) , his mechanical solution of the duplication problem . his most scientific achievement of the earth , is considered in Problem Study 6.1 ( c )