On 5 Sep 2004 at 17:14, PeterO wrote: > A sub plot in the Longitude book is the dispute between the Astronomer > Royal, Nevil Maskelyne and John Harrison, the inspired clockmaker. All due to his overly strong belief in Newton, who'd claimed that if the problem of longitude was to be solved, it would be by the astronomers and natural philosophers, not the mechanics (clockmakers). Maskelyne wasn't the only one, which indicates the god-like status that Newton had attained. > Maskelyne claimed to be able to measure longitude using the "Lunar > Distance" method, which I think precluded the need for measuring the > difference in time between two points on the earth's surface The lunar distance method determines time, not longitude. It's an astronomical clock, like Jupiter's moons. Since the motion of the moon was well understood, its position among the stars could be predicted with high accuracy. Tables listing position versus GMT were calculated and printed. If the navigator used the sextant and tedious calculations to determine the moon's position, the time could then be looked up in the table. > By the way Dava Sobel and William Andrews wrote a second version of > Longitude called "The Illustrated Longitude" which includes a parallel > story of the development of 17th century navigational instruments in > notes attached to each picture. This past spring at our kayak club's Spring Rendezvous, I gave a talk on the development of navigational instruments from ancient times to the sextant. I made the instruments out of foamcore (cardboard- laminated stiff foam) and held them together with spring clips. That way I could show how if you move this and change that, the instrument changes from, say, a quadrant to a backstaff or a backstaff to a reflecting quadrant and thence an octant. I also pointed out things like a kamal and a cross staff are two different forms of the same instrument. > William Andrews has also written a > book "The Quest for Longitude". which is top of my Christmas list:~) Something to look for! Thanks, Peter. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Sun Sep 05 2004 - 08:59:19 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:31:17 PDT