The technology for silver-coating glass mirrors, more reflective than speculum metal and not subject to tarnishing, was developed in the mid-19th century but was slow to be adopted.
A major technology advance of this time was the development of photography, permitting astrophotography, and some telescopes were tailored to this application.
A wide variety of scientific instruments were developed for use with telescopes, such as for spectroscopy and various astronomical measurements.
Early reflectors using speculum metal had some of the record-breaking apertures of the day, but not necessarily high performance.
Refracting telescopes, with lenses, especially achromatic doublets, rather than mirrors were popular in the 19th century (see also great refractor).