JF Ptak Science Books Quick Post
What is there not to like in a blackboard? Doing work on a blackboard is a definite commitment, thinking done out-loud, brain squeezings that you had to stand next to and own, creativity done on the fly with plenty of room for annotations. And so how would you accommodate an expansion of the display of thought or instruction in the 19th century? There were evidently plenty of ways around just having a big piece of slate on a wall, as these U.S. Patent Office application/grant drawings will show.
Bookish Blackboard Rolling, Infinite Blackboard
Expanding box blackboard
Rolling Blackboard, B
Multiple Rolling Blackboards
Reversible Blackboard:
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