Sentence:  It was a dark and stormy night; the rain fell in torrents — except at occasional intervals, when it was checked by a violent gust of wind which swept up the streets (for it is in London that our scene lies), rattling along the housetops, and fiercely <WSD>agitating</WSD> the scanty flame of the lamps that struggled against the darkness. 
Meaning of the word marked with <WSD> tags:  To cause to move with a violent, irregular action