Hotlicks' answer has been self-deleted. As of this moment, the two answers that are there have both received -4.
Assuming this isn't fraudulent sock-puppetry, nor simply a bandwagon effect, I believe these answers were caught in a vote-to-order war. I used to do that, before I took a nice hard look at how I vote.
With those protocols in mind, I've decided to upvote the praxinoscope answer and not upvote yours, even though it is useful. So I guess I still do vote to order, just not with arbitrary down votes.
My reasoning being that praxinoscopes provide peep-shows (but they indeed have become known as peep-shows, so +0).
Upvotes are not for "correcting" downvotes. It is not your job to take away somebody else's right to vote. Only upvote if you thought that it was a great question/answer, not because you disagreed with somebody else's downvote. –Lightness's profile
Downvotes aren't for "correcting" upvotes either.
Update: everyone's wrong.
Considering that there's three view ports, and the inner workings are a simple scroll, it's probably a Zograscope : "an optical device for enhancing the sense of depth perception from a flat picture."