Jump to content

File:H1 low 250.jpg

Page contents not supported in other languages.
This is a file from the Wikimedia Commons
From Wikipedia, the free encyclopedia

H1_low_250.jpg (250 × 294 pixels, file size: 81 KB, MIME type: image/jpeg)

Summary

Description
English: John Harrison's H1 marine chronometer. It took Harrison about five years to develop this chronometer. Its sea trial was in 1735 on HMS Centurion to Lisbon and HMS Orford returning to England. It weighs 34 kilograms (75 lb) and was originally housed in a glazed wooden case about 120 centimetres (3.9 ft) in each dimension.

Instead of a pendulum, it employs a pair of rocking bars with balls on the end and constrained with helical springs. The equal and opposite movement of these bars was less susceptible to being affected by a ships movement than a pendulum would be. Harrison's grasshopper escapement connects the bars with the rest of the mechanism. Some of the cog wheels are of wood which has self-lubricating properties. Gridirons provide temperature compensation by modifying the effective length of the helical springs.

For this invention Harrison received £250 (compared with the £20,000 offered for a full solution) from the Board of Longitude.

Harrison called it a "timekeeper".

The bar-balances like elongated dumbells do not run in conventional bearings. Instead they roll on pairs of plates set at 45° to the vertical and at 90° to each other. These plates, which only move through very short distances are on the ends of long arms pivoted near the bottom of the instrument. The counterweights to these arms are the brass knobs looking like control knobs at the very bottom.

This and other devices mean that the clock requires no lubrication.

  • Harrison Jonathan Betts National Maritime Museum, Greenwich, 2007
  • Ref: The Illustrated Longitude, Dava Sobel and William J. H. Andrews, Fourth Estate, London, 1998.

Better images: pixgood and my-time-machines.

Shot without flash, 800 ASA setting.
Date
Source Own work
Author Phantom Photographer

Licensing

I, the copyright holder of this work, hereby publish it under the following licenses:
w:en:Creative Commons
attribution share alike
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
GNU head Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.
You may select the license of your choice.

Captions

Add a one-line explanation of what this file represents

Items portrayed in this file

depicts

24 February 2011

0.1 second

6.3 millimetre

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current18:55, 24 February 2011Thumbnail for version as of 18:55, 24 February 2011250 × 294 (81 KB)Phantom Photographer{{Information |Description ={{en|1=Photograph of John Harrison's H1 clock. Low resolution for illustrative purposes only, and to discourage potential commercial use.}} |Source ={{own}} |Author =[[User:Phantom Photographer|Phantom Ph

The following 2 pages use this file:

Global file usage

The following other wikis use this file:

Metadata