How does Mark Twain use imagery in Following the Equator: A Journey Around the World?

Imagery:

"I used to take pledges - and soon violate them. My will was not strong, and I could not help it. And then, two be tied in any way naturally irks and otherwise free person and makes him chafe in his bonds and want to get him liberty."

"Horsham sits in a plain which is as level as a floor - one of those famous dead levels which Australian books describe so often; gray, bare, sombre, melancholy, baked, cracked, in the tedious long drouths, but a horizonless ocean of vivid green grass the day after a rain. A country town, peaceful, reposeful, inviting, full of snug homes, with garden plots, and plenty of shrubbery and flowers."