Evidence — Certificate of public officer. I think the paper signed by J. M. Thacher, acting commissioner of patents, was clearly inadmissible. It is not and does not purport to be a copy of any record or paper existing in the pension office, but is simply the statement of a fact within the knowledge of the gentlemen who signed it. The plaintiff was entitled to have that fact proved in the usual way, and could not legally be deprived of the privilege of cross-examination by the form in which the statement was put. I think the verdict must be set aside.