10. In the event of frequency of loss at a City Post Office, it should
be ascertained through whose hands the missing letter would pass, and
an endeavor should in this way be made to concentrate the several
losses on the guilty party.

11. It is a well established fact that a person who has once committed
theft will continue to steal, and a concentration of cases of loss, in
the manner pointed out, will certainly afford a clue to his detection.

12. Commencing each month, number each office consecutively, as it
appears in the record of cases of loss or abstraction. This will
show:--

1st. The number of cases which have occurred at any particular
office during the month; and

2nd. In each case the relative number of cases affecting each of
the offices through which any lost letter, or letter from which an
abstraction has been affected, has or should have passed.

13. It should be borne in mind that losses or abstractions may have
occurred previous to the posting of the letters or after their
delivery, and that the occurrence of two or more cases applicable to
the same party posting or receiving letters is sufficient, at any
rate, to awaken suspicion that the loss may not have taken place in
the transit of the letters through the Post Office.

14. In cases of abstraction it is very important that both the cover
and the letter from which the alleged abstraction has taken place
should be obtained. A very careful and minute examination thereof
will, in many cases, enable the Inspector to determine whether any
abstraction has really occurred, or, if it has occurred, to narrow the
suspicion down to the office where it has actually been committed.

1. Examine the flap of the letter, if necessary, by means of a
magnifying glass, and ascertain if it shows the least sign of
having been opened and re-fastened, either by slight tears in the
paper, marks of dirt, or moisture, or the application of
additional mucilage.

2. Weigh the letter with its alleged contents and see if the
weight corresponds with the amount of postage paid on the letter.

3. Carefully examine the post-marks. If the impressions or
indentations have penetrated from the cover to the letter inside,
ascertain whether there has been any change in the position of the
letter in the envelope between the time it received the post-mark
of one office and the time it received the post-mark of another
office.

This will s