What did William Herschel’s first chart of the Milky Way show?

William Herschel’s first quantitative chart of the Milky Way, produced in 1785, depicted the galaxy as a flattened disk.1

To create this chart, Herschel performed numerous star counts, which he termed "star gages," in various directions across the sky. He based his work on two primary assumptions:1
* That his telescope was powerful enough to see all the stars within our system.2
* That stars were distributed regularly throughout the system.2

He reasoned that the number of stars visible in a telescope's field of view served as a measure of the distance to the edge of the Milky Way in that specific direction. Herschel later abandoned this chart when he realized his telescopes were not powerful enough to penetrate to the galaxy's edge, and that his initial assumptions were incorrect. Nevertheless, because no better model existed at the time, his drawing was frequently reprinted throughout the 19th century.12