I'm not an electrician nor do I portray an electrician on television, so I won't try to explain the mho. However, it was the original name for a unit of electrical conductance which is now known as a siemens, after Ernst Werner von Siemens. The name was simply "ohm" spelled backwards.
I, too, learned a new word in today's puzzle: "Tread water to check out surroundings, as a whale" was SPYHOP. That word is not in my dictionaries, though, and I question if a whale is truly capable of treading water in the way that humans do.
Twice I have done month-long studies of crosswords to determine the most-commonly-used words. The results are posted on the General Discussion forum. EMU is one of the most common and I discovered that its overuse goes back much farther than I thought. Fantagraphics is reprinting all the Mickey Mouse comic strips in chronological order. The latest volume, #6, includes the strip from August 22, 1940, part of a sequence that features Mickey trying to win a contest at a theatre. The MC asks him, "Is an emu a bird, fish or a musical instrument?" Mickey replies, "It's a bird, sorta like an ostrich." The MC says, "Quite correct. And where is it found?" The audience laughs at Mickey's answer: "In crossword puzzles." There ya go!
