An aside, I believe the early computer witnessed by Lawrence Waterhouse in Cryptonomicon used this mercury column system, it was described as visibly moving up and down inside the columns.
I hadn't heard of anything like it at the time, it was an intriguing idea - I wasn't even sure Stephenson hadn't made the whole thing up.
I think the version in Cryptonomicon was based on actual sound waves (in tubes filled with air) rather than in mercury as the book mentions to noise coming from his laboratory.
I hadn't heard of anything like it at the time, it was an intriguing idea - I wasn't even sure Stephenson hadn't made the whole thing up.