You can’t make people use streets they have no reason to use. You can’t make people watch streets they do not want to watch. Safety on the streets by surveillance and mutual policing of one another sounds grim, but in real life it is not grim. The safety of the street works best, most casually, and with least frequent taint of hostility or suspicion precisely where people are using and most enjoying the city streets voluntarily and are least conscious, normally, that they are policing.
Street lights can be like that famous stone that falls in the desert where there are no ears to hear. Does it make a noise? Without effective eyes to see, does a light cast light? Not for practical purposes.
What's that big electrical cord that also connects the ship to the dock? It's not a power cord to run machinery aboard ship; it's a grounding strap, to prevent sparks from static electricity. Something else you're sure to notice on a tanker is a big warning sign about the fire hazard. Frederick Allen, the editor of American Heritage of Invention & Technology, has remarked that all tankers seem to be named No Smoking.
Moving in the city means constantly changing the axis of movement. In general, lateral movement is confined to a single plane, what’s called grade, the ground level.
Because circulation in multistory buildings is fundamentally one way—which is to say from the bottom up—the condition at the top is invariably different from that at the bottom. Rooftop circulation is the domain of Fantômas, of cat burglars and fleeing criminals, of lovers, and of those acrobatic enough to negotiate the gaps between buildings.