Which sentences in this excerpt from Mark Twains The Danger of Lying in Bed are examples of verbal irony?

In Mark Twain's "The Danger of Lying in Bed," an example of verbal irony is when he writes, "The surest way to prevent bed-sores is to lie on the back," because lying on the back can actually contribute to bedsores. Another example is "kin to ... Spiders' webs," as webs are typically fragile, in contrast to the implied strength of the relationship being described.