Note 447-55 — Scene I.—Before Prospero’s Cell.

Under the line. We can imagine that Stephano has pulled the leather jerkin or coat from the line. When he says under the line, he thinks of that as an expression sailors use when they are near the equinoctial line or equator, where the heat is intense, so strong as to take the hair or fur off the coat and make it a bald jerkin.