Why didn't the wooden bucket used by the ancients for bathing leak? I lamented the wisdom of the ancients.

Daily bathing in wooden barrels lasted until the 1970s and 1980s, and later, with the improvement of housing conditions, it was changed into a porcelain bathtub. This is not the patent of "the ancients".

Structurally, it's simple. The barrel is a jigsaw puzzle with a metal hoop outside. Because the cylinder is conical and the upper part is small, the hoop is installed from bottom to top, which fixes the relative position between the plates and closes the gap. Then, when the wood absorbs water and expands, and the outside is restrained by the barrel hoop and cannot be stretched, it will be squeezed in the opposite direction to further crush the gap, so there will be no water leakage.

Of course, the craftsmanship of carpenters at that time was different from that of carpenters today. At that time, carpenters didn't need nails and glue (or glue) to work. No matter what you do, it is natural, firm and close. This is called skill, or you don't even have to eat!