Why Newton invented the reflecting telescope and why he died of mercury poisoning
Astronomers remember Isaac Newton for inventing the Newtonian telescope. The Newtonian telescope is a reflecting telescope that utilizes a mirror instead of a lens to collect light and focus it to a point whereby a second mirror can direct the concentrated beam of light toward an eyepiece for magnification and viewing by an observer or instrument. When Newton built his telescope, he did so because he thought he could get a more accurate fugue and focus. But that is not why modern-day astronomers are grateful for Newton's reflecting telescope.
A reflecting telescope has a mirror that is supported from behind, whereas a refracting telescope has a lens which must support itself by the structural integrity of its glass. This means that there is a practical limit to the size of a refracting telescope since the larger a the lens at the front gets, the more likely the lens will distort an image due to it sagging from the weight of gravity. There is no limit to how large a reflecting mirror can be since its weight is supported from behind, preventing any distortions from sagging.
The largest refractor ever built is the 40" telescope at Yerkes Observatory, while modern reflecting telescopes have exceeded 200".
What do the Bubonic Plague, a nervous breakdown, and failing as a farmer have to do with the greatest scientific publication of all time?
Newton didn't die of mercury poisoning as a result of chemical experiments, but rather from alchemical experiments. During his incredible scientific career, Newton took a very profitable position as head of the English Mint. It is assumed he was trying to turn lead into gold because when his body was moved after burial, it was discovered that Newton had massive amounts of mercury in his body.
It was Isaac Newton who is most credited with distinguishing astronomy from astrology since his laws of gravitation and motion could be applied to the scientific study of the universe. Despite all this, Newton felt compelled to dabble in the mystical and esoteric study of alchemy to the point that it probably brought on his early demise.