A nutrition survey of pre-school children, 1967-68 Book

I've been looking for this book for decades (under the wrong title) and finally found it on a vintage children's fiction blog...and on eBay. Reading this book again after more than 40 years was one of those rare times when something actually is as good as the memory. The Diamond in the Window is a top notch children's book for any decade. Even for adults, it's both a fun and gripping read, and filled with valuable, not-too-pedantic lessons for children (and grown-ups too). The "funny uncle" character, Uncle Freddy, is a brilliant addition to the story because his nutty antics hold the reader's interest while serving as a primer to the Transcendentalist movement. It's a scintillating tale about two good little children who save the day. Loved it. I won't be letting this one go a second time.