What is the method for weighing extremely heavy objects that cannot be placed on a standard scale?

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When an object is too heavy to be weighed on a standard scale, such as millstones or large stones, the weight must be determined using a ship (vessel). The ship is placed in the water to mark the initial waterline. The heavy object is then placed in the ship, and the resulting new waterline is noted. After removing the heavy object, sand or smaller stones are added to the ship until the waterline returns precisely to the mark previously made by the heavy object. The weight of the added material (sand or small stones) is then determined by a standard scale. This weight equates to the weight of the original heavy object.