This medieval mechanical reading desk was designed to save space while allowing a number of books to be perused without getting up from one’s chair.
The inset to the illustration shows the gearing that made it work, the centre gear is designed to be stationary so that the planetary gears keep the books facing the same way as the whole wheel is rotated.
The device was illustrated in Ramelli’s book “Various Ingenious Machines” (1558) and was described as:
“A beautiful and ingenious machine, which is very useful and convenient to every person who takes pleasure in study, especially those who are suffering from indisposition or are subject to gout: for with this sort of machine a man can see and read a great quantity of books, without moving his place: beside, it has this fine convenience, which is, of occupying little space in the place where it is set, as any man of understanding, can well appreciate from the drawing. “
It’s a bit like the desktop of my computer, full of open windows!