Why did William Herschel later abandon his drawing of the Milky Way’s shape?

William Herschel abandoned his 1785 drawing of the Milky Way’s shape after realizing that his telescope was not powerful enough to penetrate to the edge of the galaxy.1

His original model was based on the assumption that he could see all the stars in the system and that they were spread out regularly. By counting the stars in various directions—a method he called "star gages"—he attempted to deduce the distance to the edge of the system. However, he eventually recognized that his instruments could not reach the galaxy's true boundary, rendering his quantitative chart inaccurate. Despite this, because no better alternative existed at the time, his drawing remained frequently reprinted throughout the 19th century.21