Thank you, friend; the words "Homo in excelsis!" are, indeed, the last words in Russel's SENTINELS FROM SPACE, published in the 1950s. Your "think it might be" was dead on! Unfortunately, I myself was not at all dead on when I said that these three words quite possibly belonged to the novel whose title and author I queried in my forum posting of May 11. These words do not belong to that novel: that novel's title and author still elude me. What I have done, and what kind individuals like you have helped me to understand that I have done, is to confound three novels, each of which--though unique--shares numerous elements with the other two. Of the three novels, I myself first sorted out the first one, MacDonald's BALLROOM OF THE SKIES (1950s); you, friend, have now sorted out the second one, Russell's SENTINELS FROM SPACE (also 1950s); only the third novel now remains to be identified by title and author. Though, in my posting of May 11, I describe that novel as probably dating to the 1980s or 1990s, maybe it--like these other two novels--actually dates as early as the 1950s. But whatever the third novel's date, the novel's plot-details as I provide them in my posting of May 11 are correct; perhaps they will yet strike a familiar chord with someone.
Terry (with fingers still crossed)