In writing to a medical doctor it is well to indicate his profession by
the letters M. D. so as to differentiate him from a D. D. It is better to
write Robert Stitt, M. D., than Dr. Robert Stitt.

In the case of clergymen the prefix Rev. is retained even when they have
other titles; as

Rev. Tracy Tooke, LL. D.

When a person has more titles than one it is customary to only give him
the leading one. Thus instead of writing Rev. Samuel MacComb, B. A.,
M. A., B. Sc., Ph. D., LL. D., D. D. the form employed is Rev. Samuel
MacComb, LL. D. LL. D. is appended in preference to D. D. because in most
cases the "Rev." implies a "D. D." while comparatively few with the prefix
"Rev." are entitled to "LL. D."

In the case of _Honorables_ such as Governors, Judges, Members of Congress,
and others of the Civil Government the prefix "Hon." does away with _Mr._
and _Esq._ Thus we write Hon. Josiah Snifkins, not Hon. Mr. Josiah Snifkins
or Hon. Josiah Snifkins, Esq. Though this prefix _Hon._ is also often
applied to Governors they should be addressed as Excellency. For instance:

His Excellency,
Charles E. Hughes,
Albany,
N. Y.

In writing to the President the superscription on the envelope should be