The tone of this poem, which describes a train, is reflective and meditative. This is shown through the perspective that the speaker introduces as she contemplates the figure of the train and describes how impressive it is. What is interesting about this poem is the way in which, through an extended metaphor, the train is described as some sort of mighty, powerful beast:
I like to see it lap the miles,
And lick the valleys up,
And stop to feed itself at tanks...
Such actions as "licking" the valleys up and the ability to feed itself at tanks suggests very strongly that the speaker views the train as an incredible beast that is able to travel vast distances with ease. It is, according to the speaker, both "prodigious" and "supercilious," and these strong adjectives suggest the power and the might of the train. Such a presentation of the train obliquely questions the relationship between man and machine. The train was invented by man to serve man, and yet the way in which it is described in this poem, as some kind of mighty animal, strongly hints that the train has more power than its creators, and thus it challenges the relationship between man and machine and asks profound questions the relationship that we have with the things that we invent for our own purposes.