---
title: The World's First Atomic Clock
author: Unknown Photographer
source: https://www.worldhistory.org/image/22336/the-worlds-first-atomic-clock/
format: machine-readable-alternate
updated: 2026-11-09
---
# The World's First Atomic Clock
_Authored by Unknown Photographer_
## Image File
[](https://www.worldhistory.org/uploads/images/22336.jpeg)
## Image Caption
The world's first atomic clock, photograph by an unknown photographer, 1955.
The photograph here shows the world's first caesium atomic clock, which was built in collaboration between Louis Essen (right) and Jack Parry (left) at the National Physical Laboratory in the UK. It measured time based on the stable frequencies of certain atoms rather than the less accurate astronomical observations of previous time-keeping devices.
National Physical Laboratory, UK.
## Cite This Work
### APA
Photographer, U. (2026, November 09). The World's First Atomic Clock. *World History Encyclopedia*.
### Chicago
Photographer, Unknown. "The World's First Atomic Clock." *World History Encyclopedia*, November 09, 2026. .
### MLA
Photographer, Unknown. "The World's First Atomic Clock." *World History Encyclopedia*, 09 Nov 2026, .
## License & Copyright
[](https://commons.wikimedia.org/wiki/File:Atomic_Clock-Louis_Essen.jpg)Based on [Wikipedia](http://www.wikipedia.org/ "Wikipedia") content that has been reviewed, edited, and republished. [Original image](https://commons.wikimedia.org/wiki/File:Atomic_Clock-Louis_Essen.jpg) by [**Unknown Photographer**](https://commons.wikimedia.org/wiki/File:Atomic_Clock-Louis_Essen.jpg). Submitted by [Alex Ram](https://www.worldhistory.org/user/alexram/ "User Page: Alex Ram"), published on 09 November 2026. The copyright holder has published this content under the following license: [Public Domain](http://en.wikipedia.org/wiki/Public_domain). This item is in the public domain, and can be used, copied, and modified without any restrictions. Please note that content linked from this page may have different licensing terms.