A cache of copper plates inscribed in the Siddha script has been recovered during the restoration of a temple tank in Thrissur. Dated to the late 5th century, the plates provide a detailed technical manual for the lost-wax casting of sacred bells and idols. The text describes precise ratios of tin, zinc, and lead required to produce specific harmonic frequencies.
This discovery confirms that ancient Indian metallurgy was deeply connected to the science of acoustics. The manuscript even details the use of specific oils to prevent oxidation, explaining why many ancient temple artifacts remain pristine today despite centuries of exposure to the elements.