After the last daily delivery carriers must return to the post office or station with which they are connected their satchels and all mail that can not be delivered. Carriers may be permitted to take their satchels home with them direct from their routes when, in the opinion of the postmaster, the interests of the service will be promoted thereby, but undelivered mail matter remaining in satchels must first be deposited in the nearest letter box. CHAPTER XVII. SPECIAL DELIVERY MESSENGERS. Chance for Boys from Thirteen Years of Age to Enter Post Office Service. The Postmaster General may, in his discretion, require the delivery of special delivery matter to be made entirely by special messengers. In New York City, however, this is done solely by employes in the service. At free delivery offices postmasters will, from time to time, employ as many messengers as in their judgment may be necessary to secure prompt delivery of special matter. None but trustworthy boys over 13 years of age should be employed. The force of special delivery messengers in each office should be so arranged that a suitable number may always be on hand to secure immediate delivery of all special delivery matter at any time within the prescribed hour of the day. Each messenger, before entering upon his duties, must take the oath prescribed by law on the blank furnished. Substitute letter carriers, when not on duty in place of regular carriers, may be employed as messengers in the special delivery service, and receive the same compensation as other messengers; but such employment must not interfere with the work of the post office or free delivery. Where delivery of special delivery matter can not be promptly made by regular special delivery messengers, postmasters may cause such delivery to be made by any regular clerk or employe, who will be allowed the same compensation, and be paid and give receipt therefore in the same manner as regular messengers. Any person employed to make immediate delivery of letters or other mail matter, shall be deemed an employee of the Postal Service, whether he may have been sworn or not, or temporarily or permanently employed, and as such employee shall be liable to any penalties or punishments provided by law for the improper detention, delay, secretion, rifling, embezzlement, purloining or destruction of any letter or other article of mail matter, or the contents thereof, intrusted to him for delivery or placed in his custody.