Fog, though not so much of a factor here, is incessantly used in English detective stories. It is so obviously a convenient device for concealing crime, that it is the foundation of Richard Harding Davis's "In the Fog" and also of "A Mysterious Disappearance," "Big Bow Mystery," "The Masquerader,"
and scores of others.
Another hackneyed device is the secret panel in the wall, which slides open by pressing a hidden spring. This was overdone in sensational fiction, before Detective Stories began, but was seized upon as a valuable device for Mystery tales. But it is easily suspected, and in unsatisfactory in modern settings.
Avoid too, if you can, the packet of valuable papers that disclose secret plans of enormous political importance. This has been overdone, and the plot of Conan Doyle's "The Naval Treaty" has been paraphrased and parodied until it has become tiresome.
Another trite incident is the finding of a pistol engraved with initials, near the body of the victim. The youngest reader nowadays, knows better than to suspect the owner of those initials.
To quote from a personal letter of Mr. Burton E. Stevenson:
> "If I were to find a murdered man,—which the Lord forbid!—and should also discover beside the body a pistol with a name on it or a visiting card or a monogrammed watch charm, or anything else of a clearly identifying character, I should conclude at once that the person thus identified was not guilty. This is a weakness which often annoys me in the modern detective story. When the hero's cane is found in the bushes near the body, and everyone concludes that the hero is therefore guilty, I put the book down with a sigh of disappointment."
A fine example of this mistaken device is in "The Villa Mystery," by Herbert Flowerdew:
> The old man was staring at him stupidly. Now suddenly his face became alive again.
> "You think that I shot the master?" he whispered incredulously. "I wish to God it was me. Do you know this, Mr. Esmond?"
> He was taking from his pocket a dainty lace-edged handkerchief, and as he passed it across to the young mean, Esmond recognized the subtle perfume it carried, even before his eyes fell on the embroidered initial, and his face paled.
> "Well?" he said hoarsely.
> Mason glanced apprehensively at the door, although it was locked, and dropped his voice to an even lower whisper.
> "It was lying by the side of the master when I found him. That is why I did not send for the police. I wanted to give her time to get away."
The veriest ignoramus in the tricks of Detective Fiction would know better than to suspect the owner of that handkerchief! Again, we find this scene in
"The Circular Staircase":
> In one of the tulip beds back of the house an early blackbird was pecking viciously at something that glittered in the light. I picked my way gingerly over through the dew and stooped down: almost buried in the soft ground was a revolver! I scraped the earth off it with the tip of my shoe, and, picking it up, slipped it into my pocket. Not until I had got into my bedroom and double- locked the door did I venture to take it out and examine it. One look was all I needed. It was Halsey's revolver! I had unpacked it the day before and put it on his shaving stand, and there could be no mistake. His name was on a small silver plate on the handle.
> I seemed to see a network closing around my boy, innocent as I knew he was.
The revolver—I am afraid of them, but anxiety gave me courage to look through the barrel—the revolver had still two bullets in it. I could only breathe a prayer of thankfulness that I had found the revolver before any sharp-eyed detective had come around.
> I decided to keep what clues I had, the cuff-link, the golf-stick and the revolver, in a secure place until I could see some reason for displaying them.
The cuff-link had been dropped into a little filigree box on my toilet table.
I opened the box and felt around for it. The box was empty—the cuff-link had disappeared!
Cuff-links, or other small articles kept for clues, invariably disappear in Detective Stories, and many authors seek to mislead by such devices, but the trained reader is not to be fooled by them.
Omit the use of a magpie, raven or parrot as an instrument for stealing jewels. A bird of this sort made an effective criminal when "The Jackdaw of Rheims" was written; but, though still a plausible one, the poor bird has been overworked and deserves a rest.
And oh, young writer, avoid, as you would the plague, the introduction of shreds or threads of wearing apparel as incriminating evidence! Probably this began with Lecoq's discovery of a few threads of brown wool, which were torn off by splinters, as a man wiped snow from a beam with his coat sleeve. This was credible and even plausible, and as it was the first time such a device had appeared in detective fiction it was acceptable. But how that poor detail has been abused and tortured ever since!