The civil service commission in each such county shall require persons applying for admission to any competitive examination provided for under this article or under the rules and regulations of the commission to file in its office, within a reasonable time prior to the proposed competitive examination a formal application in which the applicant shall state under oath or affirmation:

(1) His full name, residence and post-office address;

(2) His United States citizenship, age and the place and date of his birth;

(3) His health and his physical capacity for the position of correctional officer;

(4) His business, employments and residences for at least three previous years; and

(5) Such other information as may reasonably be required, relative to the applicant's qualifications and fitness for the position of correctional officer.

Blank forms for such applications shall be furnished by the commission, without charge, to all persons requesting the same. The commission may require, in connection with the application, such certificates of citizens, physicians or others, having pertinent knowledge concerning the applicant, as the good of the service may require.

No application for original appointment shall be received on and after the effective date of this article, if the person applying is less than eighteen years of age at the date of application: Provided, That in the event any applicant formerly served as a correctional officer for a period of more than one year in the county to which he makes application, and resigned as a correctional officer at a time when there were no charges of misconduct or other misfeasance pending against him, within a period of two years preceding the date of his application, and at the time of his application resides within the county in which he seeks appointment by reinstatement, then such applicant shall be eligible for appointment by reinstatement in the discretion of the civil service commission provided he is not sixty-five years of age or over, and such applicant, providing his former term of service as a correctional officer so justifies, may be reappointed by reinstatement without a competitive examination, but such applicant shall undergo a medical examination; and if such applicant shall be so appointed by reinstatement as aforesaid, he shall be the lowest in rank in the jail next above the probationers of the office.