08-24-2013, 06:33 PM
#1
User Info
My sister sent me this site, which allows for seeing the earth's magnetic declination patterns for any year back to 1590. I hadn't realized that these changed so much over time.
http://maps.ngdc.noaa.gov/viewers/histor...clination/

This led me to read a little on Wikipedia about compasses:
"The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since about 206 BC). The compass was used in Song Dynasty China by the military for navigational orienteering by 1040-1044 and was used for maritime navigation by 1111 to 1117. The use of a compass is recorded in Western Europe between 1187 and 1202 and in Persia in 1232. The dry compass was invented in Europe around 1300. This was supplanted in the early 20th century by the liquid-filled magnetic compass." (See the Wikipedia article for more information about dry and liquid compasses: http://en.wikipedia.org/wiki/Compass)

184 12,003
Reply
 08-24-2013, 07:40 PM
#2
User Info
Yes it changes.

Check any topo map and it will tell you what the declination was when the map was printed and how to correct for it's drift over time to make the map accurate for today.

GPS is nice, but back of beyond I wouldn't be w/o a map and compass (or a GPS).

32 6,309
Reply
 08-25-2013, 09:30 PM
#3
User Info
Thanks for the link, John! Smile

75 20,883
Reply
 08-26-2013, 05:05 AM
#4
  • ischiapp
  • Senior Member
  • Ischia, Naples, Italy
User Info
Thank You John,
anyway ... until the postman can find my home to give my things Angel Cool Tongue Biggrin Lightbulb

0 1,096
Reply
 08-26-2013, 07:02 AM
#5
User Info
Nice find - and it certainly shows that "North" and North is two very different things Smile

3 3,580
Reply
 09-14-2013, 08:19 AM
#6
User Info
"Control D" Page Bookmarked!! Thanks for the link!!

0 74
Reply
Users browsing this thread: 1 Guest(s)