The Diamond Lens
Hard Sci Fi From 1858

"They say now that I am mad; but they are mistaken... Young men's associations invite me, pay me, and laugh at me while I lecture. 'Linley, the mad microscopist,' is the name I go by."

In 1858, microscopy is the cutting-edge science of the day. The cell nucleus had been seen, and soon chromatic aberrations were abolished as multi lens microscopes came into being. One young man becomes obsessed with creating the perfect microscope, failing over and over again until in desperation he communes with the spirit of Antonie van Leeuwenhoek, inventor of the microscope, who tells him the key to a perfect lens. Using electromagnetic currents, he finally succeeds.
There follows a tale of murder, revelation, tragically doomed love, and being laughed at by students.

This is the first major microcosmic story, written over a century before before greats like Theodore Sturgeon's Microcosmic God, Asimov's Fantastic Voyage, Ant-Man, Rick and Morty, or Horton Hears a Who!