Part of my study:
On March 2, 1833, the Senate and House passed a bill:
"… prescribing the mode by which patents for public lands shall be signed and executed”. That same day, President Andrew Jackson sent to the Senate his nomination of his secretary, Andrew J. Donelson to be the Secretary authorized under the act “prescribing the mode by which patents for public lands shall be signed and executed”. Therefore all Land Grants after this authorization are signed by a secretary.