From 1853 he was chief assayer to the United States assay office in New York City when that office was established, but he continued to take an interest in botanical teaching until his death.
Fra 1853 var han ledende probermester ved USAs proberkontor i New York City, dvs. fra den dag, da dette kontor blev etableret, men han fortsatte med at interessere sig for undervisning i botanik indtil sin død.