Dashiel Hamett's Rules for Detective Writers
(1) There was an automatic revolver, the Webley-Fosbery, made in England some years ago. The ordinary automatic pistol, however, is not a revolver. A pistol, to be a revolver, must have something on it that revolves.
(2) The Colt's .45 automatic pistol has no chambers. The cartridges are put in a magazine.
(3) A silencer may be attached to a revolver, but the effect will be altogether negligible. I have never seen a silencer used on an automatic pistol, but am told it would still make quite a bit of noise. "Silencer" is a rather optimistic name for this device which has generally fallen into disuse.
(4) When a bullet from a Colt's .45, or any firearm of approximately the same size and power, hits you, even if not in a fatal spot, it usually knocks you over. It is quite upsetting at any reasonable range.
(5) A shot or stab wound is simply felt as a blow or push at first. It is some little time before any burning or other painful sensation begins.
(6) When you are knocked unconscious you do not feel the blow that does it.
(7) A wound made after death of the wounded is usually recognizable as such.
(8) Fingerprints of any value to the police are seldom found on anybody's skin.
(9) The pupils of many drug addicts' eyes are apparently normal.
(10) It is impossible to see anything by the flash of an ordinary gun, though it is easy to imagine you have seen things.
(11) Not nearly so much can be seen by moonlight as you imagine. This is especially true of colors.
(12) All Federal snoopers are not members of the Secret Service. That branch is chiefly occupied with pursuing counterfeiters and guarding Presidents and prominent visitors to our shores.
(13) A sheriff is a county officer who usually has no official connection with city, town or state police.
(14) Federal prisoners convicted in Washington, D.C., are usually sent to the Atlanta prison and not to Leavenworth.
(15) The California State prison at San Quentin is used for convicts serving first terms. Two-time losers are usually sent to Folsom.
(16) Ventriloquists do not actually "throw" their voices and such doubtful illusions as they manage depend on their gestures. Nothing at all could be done by a ventriloquist standing behind his audience.
(17) Even detectives who drop their final g's should not be made to say "anythin'" an oddity that calls for vocal acrobatics.
(18) "Youse" is the plural of "you."
(19) A trained detective shadowing a subject does not ordinarily leap from doorway to doorway and does not hide behind trees and poles. He knows no harm is done if the subject sees him now and then.
(20) The current practice in most places in the United States is to make the coroner's inquest an empty formality in which nothing much is brought out except that somebody has died.
(21) Fingerprints are fragile affairs. Wrapping a pistol or other small object up in a handkerchief is much more likely to obliterate than to preserve any prints it may have.
(22) When an automatic pistol is fired the empty cartridge shell flies out the right-hand side. The empty cartridge case remains in a revolver until ejected by hand.
(23) A lawyer cannot impeach his own witness.
(24) The length of time a corpse has been a corpse can be approximated by an experienced physician, but only approximated, and the longer it has been a corpse, the less accurate the approximation is likely to be.