---
title: "Carnegie Steel Mill Opens"
year: 1875
country: "United States"
canonical: "https://recap.at/1875/carnegie-steel-mill"
slug: "carnegie-steel-mill"
recapType: "global_event"
startDate: "1875-01-01"
---

# Carnegie Steel Mill Opens

> Andrew Carnegie's Edgar Thomson Works introduced the Bessemer process to American steelmaking at scale, triggering industrial transformation and labor upheaval.

## Summary

The Carnegie telescope is a twin 20-inch (510 mm) refractor telescope located at Lick Observatory in California, United States. The double telescope's construction began in the 1930s with a grant from the Carnegie institution, although it was not completed until the 1960s when a second lens was added. The telescope is not designed for visual observation, rather it has two lenses used for taking photographs for a specific wavelength recorded on a film emulsion. It was used for photographic sky surveys in the late 20th century, which were successfully completed.

## Sources

- [Carnegie telescope](https://en.wikipedia.org/wiki/Carnegie_telescope) - Wikipedia

---
Canonical: https://recap.at/1875/carnegie-steel-mill