R.M.S. Titanic.
The question on vacuum cleaners on the Titanic always bothered me. I'm certain there were several of them in use. However, as it was 1912, very few of the companies like Hoover were even known yet. Being British, Cecil H. Booth had outfitted several buildings with his suction machines. So when I bought the book 'Discovery of the TITANIC' the first thing I looked for was a vacuum cleaner. Obviously, the researchers didn't think a vacuum cleaner was important.
Keep in mind that in September, 1985, when Robert Ballard found Titanic, I was digging research for the V.C.C.C. newsletters, and this would have been a great topic, so I wrote to Robert Ballard. As I said, no responce!
The question still bothers me, being a man who's interested in history, especially the non electric, and early electric machines of 1900 - 1920, I know, something, was used.
I'll continue searching.