has an interesting article
in New Scientist about the Mundaneum, a mid-twentieth century effort to create a vast, interlinked archive, like a "proto-internet," using index cards. But what caught my eye was the first paragraph:
UNLIKELY as it sounds now, the hottest thing in information technology was once the index card. In the US, for instance, the War Department struggled with mountains of medical files until the newfangled method of card filing was adopted in 1887. Soon hundreds of clerks were transcribing personnel records dating back to the War of Independence. Housed in Ford's Theatre in Washington DC - the scene of Abraham Lincoln's assassination a generation earlier - the initiative succeeded a little too well. Six years into the project, the combined weight of 30 million index cards led to information overload: three floors of the theatre collapsed, crushing 22 clerks to death.
It's like the old urban legend about a library sinking because the engineers forgot to include the weight of the books in their calculations. Though I'm not sure that the weight of the index cards was the cause of the collapse of Ford's Theater. The wikipedia article
about the Ford's Theater disaster (I was surprised to discover there is
a wikipedia article about such a now obscure event), notes that workmen had removed part of the theater's foundation and had failed to shore up the building above it. Thus, it came crashing down.
So the Ford's Theater disaster may not be a real-life example of the sinking-library urban legend. But I'm sure there's an example somewhere of a library that collapsed because of the weight of its books.