NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

HOME

Re: Chronometer rating
From: Lars Bergman
Date: 2024 Jan 24, 12:27 -0800

Frank, you wrote "navigators did take chronometers to "clock shops" for rating. It wasn't a rare thing". This is very interesting; I have never, yet, came across such information. Could you please provide some evidence or references to confirm this statement.

I am aware of the difference between a chronometer's error (at a certain time), and its rate. If you don't have some kind of "speed meter" that directly measures the "speed" of the clock (with an accuracy on ppm-level) then you have to determine the rate indirectly by taking the difference of errors measured at different times and divide by the time interval between those measurements. Exactly as you propose in your imagined scenario.

Some ports had time signal facilities, time balls have been discussed on NavList in recent years. Attached is an interesting document showing the rating of two chronometers aboard a not yet with certainty identified Finnish (then Russian) vessel, at Saint John, New Brunswick. It is probably from the late 1890-ies. During a period of nearly a month the time ball was watched when it was released at 1 hour p.m. local mean time. This resulted in seven error determinations for each chronometer. If anyone is interested, please provide the best estimate of error on GMT at Greenwich mean noon of 15 September, and the daily rate, for each chronometer respectively. Use of contemporary calculation methods is appreciated.

Lars

File:

What is NavList?

NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

NavList is more than an online community... more about that another day.

© Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

Subject:
Author:
Start date:	(yyyymm dd)
End date:	(yyyymm dd)

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

NavList

What is NavList?

Join / Get NavList ID Code

Retrieve a NavList ID Code

Email Settings

Custom Index

Add Images & Files
Name or NavList Code:	Email:

Name:
	(please, no nicknames or handles)
Email:

NavList ID Code: