Part 6/8:
Adding to the custodial burdens, lighthouse keepers were often exposed to hazardous substances like mercury, which not only fueled the lights but also posed serious health risks. The presence of mercury in tasks like maintaining the Fresnel lenses contributed to an environment rife with potential insanity. As if by fate, the phrase "mad as a hatter," often associated with the hat-making industry that used mercury, led some to propose a similar phrase for lighthouse keepers.