fleeting

Passing quickly; of short duration.

Architecture, sculpture, painting are static arts. Even in literature "our flying minds," as George Meredith says, cannot contain protracted description. It is so; for from sequences of words they must assemble all the details in one simultaneous impression. But moments of fleeting beauty too transient to be caught by any means less swift than light itself are registered on the screen.

As they passed, accelerating, on to the bridge and felt the first bite of the incline beyond, one had a fleeting glimpse of driver and fireman, illumined as by the fires of hell, the one tugging at the regulator handle, the other shovelling for dear life.

That which flees, especially quickly; fugitive.

An automatic operation mode of an absolute signal that reserves a route for several trains following one another, without the need for dispatcher to re-set the route for each train.