TIL Charles Babbage worked on improving the efficiency of the adders in his Analytical Engine with something he called an "anticipating carriage" for the carries. He hoped to improve on a sort of ripple carry he implemented in the Difference Engine that apparently took 20 seconds to complete?

Sydney Padua provides a simulated demo:

Via Ken Shirriff:

Regardless of computing technology, some of the underlying problems are always the same.

Great! My understanding is that the speed of Babbage's carry mechanism is limited by the speed of sound in brass - it's not instantaneous, which seems important to me. But it's very fast, and certainly fast enough.


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