What is the meaning of that sentence ? Sentence is "At the start of the year unemployment was plumbing new lows."
Can you explain why plumbing is used and what "new lows" mean ? Thanks.
Solution 1:
You have to understand the nautical connotation. A sailor would "plumb the depths" of a harbor using a cord with a lead (plumbum) weight on the end of it. In fact, this is where Mark Twain got his moniker.
So, "plumbing new lows" means going "deeper" than previously (in recent history) seen.
(And I'll note that "plumbing" in the sense of pipes gets its name from the common use of lead pipes in prior eras.)