Caution in finding North by bisector line of a horizontal watch
by tonytran2015 (Melbourne, Australia).
Click here for a full, up to date ORIGINAL ARTICLE and to help fighting the stealing of readers’ traffic.
#find north, #finding North, #bisector, #horizontal watch, #inclined watch, #limitation, #caution.
Caution in finding North by bisector line of a horizontal watch (blog No. 10).
There is currently wide advocating for the application of the method of finding North direction by “the bisector line of a horizontal watch”. There have even been proposals to use the method on the new and full Moon as the position of the Sun can be determined from the position of new or full Moon [1], [2]. However people should remember the basic limitations of the method and if they exceed its hard limitation perilous and catastrophic consequences (such as direction errors of 90 degrees or even direction reversal sending people astray) may result.
1. POSSIBLE PERILOUS SITUATIONS.
Figure: Limitations of finding North by the bisector of a horizontal watch. The picture in the title page shows the two applications to Southern (red direction line) and Northern(green direction line) hemispheres of the method of “bisector line of a horizontal watch”. The limitations for each case are clearly displayed in yellow.
Here are the few possible perilous situations:
a/- On any summer solstice day, at latitude +23.5 degrees, the Sun rises in ENE, travels to a point in the East direction, to the zenith, to a point in West direction, then sets in WNW.
b/- On any summer solstice day, at latitude +20 degrees, the Sun rises in ENE, travels to a point in North direction, then sets in WNW.
If the method of “bisector line of a horizontal watch” is used for case a, the error will be a flipping +/- 90 degrees near to noon while if it is used for case b, the error will be a devastating 180 degrees around noon time.
With such situations in mind, people using the method of “bisector line of a horizontal watch” should heed the warning to preserve its accuracy and NOT to use it during their summers in zones near to the equator, with less than 30 degrees latitude (low temperate and tropical zones).
Users of “bisector line of a horizontal watch” should be even more cautious when they guess the position of the Sun in the sky from the position of the Moon and then apply the method. A perilous situation may arise as illustrated in the following:
c/- On a summer solstice day, at latitude +26 degrees, the Sun rises in ENE, travels to a point in South direction at mid-day then sets in WNW. However at night the Moon rises in ENE, may travel to a point in North direction at mid-night then sets in WNW. Note here that the Moon may go to the North while the Sun goes to the South at their highest altitudes and the Moon does not necessarily retrace the path of the Sun 12 hour later, as the proponents of the extension had wished.
So users should be even more cautious when guessing the position of the Sun in the sky from the position of the Moon. They should heed the warning to preserve its accuracy and NOT guess the position of the Sun from the Moon to use the method in zones near to the equator, with less than 40 degrees latitude (temperate and tropical zones).
2. UPDATING TO A SAFER METHOD.
Figure: Summary of my new method of finding North by a watch.
Figure: My new method of finding North by a watch.
Figure: My new method of finding North by a watch.
For accuracy and safety, it is worthy for users to switch to my new method of “inclined bisector line of a tilted vertical watch” [3]. It has no latitude limttion and requires only the declination of the Sun and the simple knowledge that the Sun is rising or falling.
References
[1]. Unknown Author. Use the moon and a watch to find north, Boy’s Life magazine ,http://boyslife.org/video-audio/134162/use-the-moon-and-a-watch-to-find-North, 2011 Mar.
[2]. Frank Williams, Finding North By The Moon In The Southern Hemisphere, BushcraftNZ,http://bushcraft.org.nz/m/blogpost?id=5745113%3AB… 2011 Jul 24.
[3]. tonytran2015, Finding accurate directions using a watch, Additional survival tricks, wordpress.com, Finding accurate directions using a watch, https://survivaltricks.wordpress.com/2015/05/19/finding-accurate-directions-using-a-watch/, posted on May 19, 2015.
RELATED SURVIVAL blogs
Finding accurate directions using a watch, posted on May 19, 2015 .
Finding accurate directions by a watch .. Posted on May 12, 2015..
, posted onShadow stick navigation and graph of solar paths, posted on August 19, 2016
Navigating with an AM MW radio receiver, posted January 17, 2017
The Scorpius constellation, posted January 8, 2017, The Orion constellation., posted December 26, 2016, Rice as emergency food., Using GPS in off-grid situations, Slide Sky-Disks with grid masks showing azimuths and altitudes, Slide Sky-Map for displaying tropical stars.
Click here for my other blogs on
SURVIVAL
SURVIVAL CONTENTS BLOG IMAGE OF SURVIVAL CONTENTS
MONEY CONTENTS BLOG IMAGE OF MONEY CONTENTS
SOCIAL ISSUES CONTENTS BLOG IMAGE OF CONT. OF SOCIAL ISSUES
LIVING BLOG LIVING CONTENTS BLOG IMAGE OF LIVING CONTENTS
HOW TO BLOG HOW TO CONTENTS BLOG IMAGE OF HOW TO CONTENTS
Click here go to Home Page (Navigation-Survival-How To-Money).
ARCHIVAL HOME PAGE CONTENTS HOME PAGE BLOG IMAGE OF CONTENTS HOME PAGE
Good day I am so delighted I found your webpage, I really found you by accident, while I was searching on Bing for something else, Regardless I am here now and would just like to say thanks for a remarkable post and a all round exciting blog (I also love the theme/design), I don’t have time to read through it all at the minute but I have book-marked it and also added your RSS feeds, so when I have time I will be back to read a lot more, Please do keep up the superb work.|
LikeLike
Greate post. Keep writing such kind of information on your site. Im really impressed by your site.
LikeLike
Does your site have a contact page? I’m having problems locating it but, I’d like to send you an email. I’ve got some creative ideas for your blog you might be interested in hearing. Either way, great website and I look forward to seeing it develop over time.|
LikeLike
Remarkable things here. I’m very glad to peer your article. Thank you so much and I am looking ahead to contact you. Will you kindly drop me a mail?|
LikeLike
With havin so much content do you ever run into any issues of plagorism or copyright infringement? My site has a lot of completely unique content I’ve either created myself or outsourced but it seems a lot of it is popping it up all over the internet without my authorization. Do you know any solutions to help prevent content from being stolen? I’d genuinely appreciate it.|
LikeLike
I think this is one of the most important information for me. And i’m glad reading your article. But want to remark on some general things, The web site style is wonderful, the articles is really great : D. Good job, cheers|
LikeLike
It’s an amazing piece of writing designed for all the online people; they will take advantage from it I am sure.|
LikeLike
These are genuinely impressive ideas in concerning blogging. You have touched some good factors here. Any way keep up wrinting.|
LikeLike
It’s awesome designed for me to have a site, which is useful in support of my know-how. thanks admin|
LikeLike
My spouse and I stumbled over here different website and thought I might as well check things out. I like what I see so now i am following you. Look forward to exploring your web page again.|
LikeLike
Great post! We are linking to this great post on our site. Keep up the great writing.|
LikeLike
I know this website presents quality based articles and other material, is there any other website which gives these things in quality?|
LikeLike
Excellent blog post. I absolutely appreciate this website. Stick with it!|
LikeLike
Hi, I do believe this is a great site. I stumbledupon it 😉 I will revisit once again since I book marked it. Money and freedom is the greatest way to change, may you be rich and continue to guide other people.|
LikeLike
Thank you for your goodwish. May I wish you with the same.
LikeLike
Thank you Rifleman III, for reposting.
LikeLike
[…] Source: Caution in finding North by bisector line of a horizontal watch. […]
LikeLike