The emergence of public electric lighting near the end of the 19th century has to rank among crime's greatest deterrents. At the dawn of the 1800s, all-enveloping darkness (punctuated by candlelight) ruled the night. During the following decades, lighting's nonlinear evolution hurtled through whale oil, kerosene, coal gas, arc lighting, and incandescence--the last, which dealt a game-changing blow to street-based crime.
. . . lighting companies marketed their product as nothing less than a police force on a pole, notes Ernest Freeberg in his 2013 book, The Age of Edison. After nightfall, urban parks became notorious danger zones, a haven for the city’s dregs and an infernal playground of indecency. Now all that could end, not by converting sinners or reforming criminals, but by harnessing light’s power of exposure. As the mayor of Baltimore put it, ‘an electric light is a nocturnal joy to an honest man, but a scarecrow to a thief.'
The Fog of Crime
Fog aided and abetted criminals as well, adds Christine Corton in her rich sociocultural study, London Fog: The Biography (2015).
[Fog] allowed the criminal, the deviant, and the transgressive to roam the streets unhindered and unobserved. And it placed them in a position to impose their authority on the respectable.
In 19th and early 20th century London, fog became a dreaded smoke screen for pickpockets, muggers, and murderers, playing an enabling role in Bleak House, The Strange Case of Dr. Jekyll and Mr. Hyde, Sherlock Holmes mysteries, and The Lodger, which proved grist for one of Alfred Hitchcock’s earliest films. (Ironically, in real life, Jack the Ripper, writes Corton, did his iconic work on clear nights.)
In the 19th century, fogs would roll in, making outdoor gas lights useless. Carrying ignited tar-dipped sticks, link-lighters—most of them teenage boys—would guide patrons through the mists. More than a few of the lads doubled as pickpockets or led clients into traps in cahoots with confederates.
Much more than an account of crime, London Fog views its namesake literally and figuratively as a toxic consequence of the coal-fired Industrial Revolution and London’s breakneck urban development. And it explores fog’s disorienting power to obscure societal boundaries as well.
Fog [writes Corton] became a symbol for the threat to the clear outlines of a hierarchical social order as it dissolved moral boundaries and reassuring certainties with obscurity and doubt.
Out of Sight, Out of Mind
Darkness and fog camouflage misdeeds. Put rural isolation on the criminal's list of smokescreens as well, advises Conan Doyle via Sherlock Holmes in The Copper Beeches:
You look at these scattered houses, and you are impressed by their beauty, [Holmes tells Watson.] I look at them, and the only thought which comes to me is a feeling of their isolation and of the impunity with which crime may be committed there.
Good heavens!” [Watson] cried. Who would associate crime with these dear old homesteads.
They always fill me with a certain horror, [retorted Holmes]. It is my belief, Watson, founded upon my experience, that the lowest and vilest alleys in London do not present a more dreadful record of sin than does the smiling and beautiful countryside.