In the first Sherlock Holmes story, he identifies the brand of cigar which a murderer smoked by its ash. As he explained to Dr. Watson:

I have made a special study of cigar ashes—in fact, I have written a monograph upon the subject. I flatter myself that I can distinguish at a glance the ash of any known brand, either of cigar or of tobacco. It is just in such details that the skilled detective differs from the Gregson and Lestrade type.

I wonder if anyone ever read this monograph.

I should, perhaps, explain my curiosity, as well as my meaning. This scene reminds me of a list of 20 rules for detective fiction which S.S. Van Dine wrote in 1920. The twentieth rule included a list of then-overused plot elements:

20. And (to give my Credo an even score of items) I herewith list a few of the devices which no self-respecting detective-story writer will now avail himself of. They have been employed too often, and are familiar to all true lovers of literary crime. To use them is a confession of the author’s ineptitude and lack of originality.
A. Determining the identity of the culprit by comparing the butt of a cigarette left at the scene of the crime with the brand smoked by a suspect.
B. The bogus spiritualistic séance to frighten the culprit into giving himself away.
C. Forged finger-prints.
D. The dummy-figure alibi.
E. The dog that does not bark and thereby reveals the fact that the intruder is familiar.
F. The final pinning of the crime on a twin, or a relative who looks exactly like the suspected, but innocent, person.
G. The hypodermic syringe and the knockout drops.
H. The commission of the murder in a locked room after the police have actually broken in.
I. The word-association test for guilt.
J. The cipher, or code letter, which is eventually unravelled by the sleuth.

As you can see, identifying the culprit by the brand of cigarette he smokes was hackneyed by 1920. Granted, that’s 33 years after the publication of A Study in Scarlet. Moreover, a thing being hackneyed implies that it was commonly used. And, of course, identifying the brand of a cigarette by its end is not the same thing as identifying a cigar by its ash.

Still, when I think over the golden age detectives with which I’m familiar (that, admittedly, mostly come after 1920), identifying people by their unusual preference in tobacco was quite uncommon. Indeed, the only instance I can recall where tobacco brand comes up as a means of identification at all was a red herring in the Miles Bredon story The Three Taps by Fr. Ronald Knox (published in 1927). I can’t remember it at all in Poirot, Lord Peter Wimsey, or Father Brown. I’ve only read two Dr. Thorndyke stories, but neither of them ever features identification via tobacco products. My memory may simply be failing me, but I’m not sure that cigar ash was ever used for identification again even by Mr. Sherlock Holmes. In The Hound of the Baskervilles, he identified Watson by a cigarette end, not by ash.

Overall, the use of identification by tobacco products (or a favorite candy wrapper, etc) occupies a very curious place in detective fiction. We can probably lump these in with other identifying things, such as monogrammed handkerchiefs, cigarette cases, fingerprints, the victim having written the murderer’s name in his own blood, etc. What these things all have in common is that they are simple evidence. If they mean what they seem to mean, no cleverness is required in order to catch the murderer. That is, no cleverness is required on the part of the reader.

At least in the very early 1900s, some cleverness on the part of the detective was required to take finger marks. Occasionally even modern shows will have a police detective using some clever means to take fingerprints off of an unusual surface in a low-tech setting. All of that may be interesting, but it is not very satisfactory for the reader. It is the fictitious equivalent of watching a reality TV show about someone doing his job with cameras following along. There’s nothing mysterious about finding out that, after some tricky work, the fingerprints of Mr. John Smithington were found on the knife plunged into the back of his creditor, Mr. Dalrymple Worthorford, so the police went and arrested him and he confessed. It might possibly be interesting that if one mixes equal parts vanilla icecream, superglue, and hand sanitizer one can cause fingerprints on cork-bark handles to fluoresce under infrared light (I made all that up), but if all that happens is the detective asks his assistant for these items, he gets them, then shines the light and takes a picture of the fingerprints, we might as well have been watching a science show for children.

The problem, then, is that for our mystery story to be a mystery story, the simple clues must be, in some measure, misleading. They tend to be misleading in only two ways, however. Either they mean that the murderer is trying to frame someone, or else they mean that the person they identify was at the scene of the crime (probably) before or (possibly) after it occurred. These are great features of a mystery story, but they are only sometimes used, and of all of the ways to use them, cigar ash is probably the weakest form of evidence to achieve the desired end. (Cigarette ends are not that much stronger, unless one is going to drag in modern forensic teams and do DNA analysis, but that is largely to drain the fun out of the story.)

All of which adds up to why I wonder whether anyone ever read Mr. Holmes’ monograph on cigar ash. There have been many detectives since Holmes with approximately his brilliance and attention to detail. I don’t know whether any of their authors have ever given them cigar ash to identify, though.