A Simile for Her Smile
Simile is a technique when we describe something. The speaker in this poem compares a girl's smile to the arrival of a packet. The speaker must be like the girl, and when he thinks of her smile his thoughts are interrupted and he can forget other unpleasant things. His mind is full of nothing but her smile. It is just like when a packet comes, the drawbridge rise, and the idling motors have to sit on each side. Her smile is the most important of all.
I think the speaker not only compares her smile to the pocket, but also his memory for her smile. " the slip/ Slip of the silken river past the sides," The speaker uses two 'slip' here because he tries to say that her smile appears so slowly on her face that it is like the ripples the boat makes when it goes through a river. Also the ripples are the symbols for his memory, slowly come to his brain and go through it without leaving any track. It is like the pocket, too. After it passes by, the traffic is still hasty, and the bridge falls down as usual. Besides, the boat also represents the girl. She has leave him away, and the only thing she left is the memory of her smile.
Though it looks like nothing happened, the cascades and the memory do have some influences on the river and the speaker's mood.