The Governor shall appoint a private secretary, who shall enter in books kept for that purpose all such letters, written by and to the Governor, as are official and important, and such other letters as the Governor shall think necessary. Such books shall be deposited in the office of the executive by the private secretary, and there carefully preserved, and the Governor shall produce the same before the General Assembly whenever requested. (1868-9, c. 270, ss. 33, 34; Code, ss. 3326, 3327; Rev., s. 5330; C.S., s. 7638.)