This is the 1984 edition, which I understand to be the first edition of the series of CONCISE Encyclopedias garnered from the definitive 14-volume set of McGraw Hill (not Concise) Encyclopedia of Science and Technology.  The volume is huge and may weigh in at 25 pounds or more, but it has EVERYTHNG in there.  This would make a great gift for a bookworm child (see pic of the "Little Nerd").  Not good for on-the-toilet reading!  But I would have loved this monster as a kid.  Great, easy text and hundreds of figures, photos and plates.  Like new.