This is because, according to Archimedes' principle of displacement, floating objects displace their own weight in water.
这是因为,根据阿基米德的位移原理,漂浮物在水中会转移自身的重量。
It wasn't until 1906 that a scholar came across the prayer book in a library and realized it was a palimpsest, and that the underlying layer of texts could only have come from Archimedes.