Marking time in the 1200’s

March 19, 2025

Written by Editor

Image: RNT Foundation

What’s new: While visiting Ragusa, Italy, we discovered a way of marking the hours of the day we had not heard of before – Italic hours which count the number of hours since the last sunset.

Why it’s important: Timekeeping has been essential to ordering life, at least since the invention of the sundial. But like Einstein’s description of time as “relative,” so is how the hours of the day are counted.

What else to know: 

  • At the top of the image you can see the gnomon (the stick on a sundial that casts a shadow). This one has a hole at the end so that it both casts a shadow and has a pinpoint of sunlight come through near the end of the shadow.
  • This sundial is on the western wall of a church, so it begins with 18 hours after the last sunset.
  • This method of marking the hours of the day was instituted first by Arab cultures around the year 1200.
  • Another method was “Babilonic” which count the hours remaining until sunset. So on the below sundial the “18” would be a “6,” the “19” would be a “5” and so on.

 

 

What Can YOU Do? How Can YOU Help?

PNT is the quiet backbone of everything but too many leaders still don’t see the risk.

But you do. You understand the systems, the dependencies, the failure chains. That insight is rare — and it’s exactly what your country needs right now. Contact your government leaders and industry decision-makers and tell them resilient PNT isn’t a feature — it’s the foundation everything else depends on.

Start the Conversation

Use our Resilient PNT Key Talking Points to make the case.

U.S. Advocates

Find your representatives at Congress.gov, then use our email template to reach them in minutes.

When you get a response, let us know. Every conversation strengthens the mission.

More PNT News

New Company for Broadcast Positioning System – NAB

New Company for Broadcast Positioning System – NAB

Image: Shutterstock What's new: The National Association of Broadcasters (NAB) has formed a separate company to develop, advocate for, and deploy the Broadcast Positioning System (BPS). Why it's important: NAB has put increasing effort behind BPS since its inception...

Standalone Magnetometry Is the New GPS – IEEE Spectrum

Standalone Magnetometry Is the New GPS – IEEE Spectrum

Image: Shutterstock What's new: An article about forms of navigation using aspects of the earth's magnetic field.  Why it's important: Autonomous navigation is becoming more interesting for a number of applications in a world where interference with GNSS is becoming...

Munich 9 Years On: Same Message, More Urgency – Inside GNSS

Munich 9 Years On: Same Message, More Urgency – Inside GNSS

Image: Shutterstock What's new: RNTF President Dana Goward's column for the May/June edition of Inside GNSS+. Why it's important: It discusses a PNT example of how concern within the tech community does not necessarily turn into action by political leaders. Or at...

US Congress hearing on PNT –  June 4th

US Congress hearing on PNT – June 4th

Image credit: House Energy and Commerce Committee What's new: A congressional hearing titled Where Are We?: Examining Positioning, Navigation, and Timing Capabilities in the United States. Why it's important:  The hearing is being held by the Communications and...

Get PNT News in Your Inbox