Saturday, January 29, 2011

How did sailors measure longitudes and latitudes 100 years ago? 

The first sat nav device, called the sextant, enabled sailors to measure longitudes and latitudes 100 years ago. The sextant was designed to find longitude by measuring the angular distance between the moon and a nearby star. It was also used on land and to find latitude at sea. A sextant is similar to an octant, but more powerful and precise. The arc extends 60 degrees or more and measures angles of 120 degrees or more. Sextants were traditionally made of brass, with scales graduated on sliver. Modern sextants are often made of plastic. Most have telescopic sights. Therefore, sailors knew their exact position and thus would be able to adjust the course as necessary and check on progress.

6 Comments:

At February 11, 2011 at 6:16 PM , Blogger Vinitha J said...

thank you Cherie and Nicole for your prompt modifications to your blog. - Miss J

 
At February 18, 2011 at 10:56 PM , Blogger Alison Corinne said...

Why do they need to measure longtitudes and lattitudes?
Corinne Tham 1-2

 
At February 19, 2011 at 1:41 AM , Blogger CJ said...

Hmmm...I wonder. How long ago was latitudes and longitudes invented? And regarding to Corrine, I also want to ask why they need to measure longitudes and latitudes?
Chrystal Ng 1-2

 
At February 20, 2011 at 1:56 AM , Blogger FaithJoanne said...

Same question- why do sailors need to measure the loongitudes and latitudes? Has it got to do with looking for directions, since that's all they do? Or is it to find stars?

 
At February 23, 2011 at 5:05 AM , Blogger Alison Corinne said...

I think that the sailors needed to measure the longitudes and latitudes for navigation. As sailors then,about 100 years ago, did not have the privilege of using technology we have nowadays,I think they were able to navigate using this tool. Anyways, interesting post!
Alison Choo 1-2

 
At February 25, 2011 at 5:19 AM , Blogger Jessica said...

Why are sextant traditionally made of brass while modern sextants are made of plastic? What is the diffence? Which is better?

 

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