Sun Dial: Scientific




Search  Inquiry Net

Back ] Home ] Up ] Next ]

Axe, Boy Scout
Axe, Saw, Forestry
Axe, Saw,  Knife
Axe Use: Beard
Axe Use: Seton
Axe Use: Traditional
Axe Throwing
Beds, Woodcraft
Bedding Materials
Bicycle Maintenance
Birch-Bark Torch
Bird Houses
Blocks Tackles Purchase
Blood Red Cross
Broom: Camp or Witch's
Camp Hygiene
Camp Planning
Campfire Programs
Chuck Box Riddance!
Compass Bear Song
Compass, Home-Made
Cotton Kills Bear Song
Deduction in Tracking
Deduction & Detective
Edible Plants
Equipment, Leader
Equipment, Personal
Equipment Maintenance
Equipment, Lightweight
Equip, Pickle Bucket Camp
Field Signals
Fire Building
Fire Laying
Fire Lighting
Fire Starters
Fire: Rubbing-Stick
Fire Types, Wood Types
Fire Council Ring
Fires: Woodcraft
First Aid
First Class Journey
Flint & Steel
Gesture Signals
Ground to Air Signals
Handicraft Stunts
High Adventure
Hike Planning
Indian Sundial Clock
Insect Collecting
Insect Preserve
Indian Well
Knife & Hatchet
Knots, Bends, Hitches
Knots: Diamond Hitch
Knots: Lashings
Knots: Rope Work
Knots: Seton
Knots: Traditional
Knots & Whipping
Lashing Practice Box
Lace or Thong
Learn by Doing
Leave No Trace
Leave No Trace
Local Knowledge
Log Ladders, Notched
Logs: Cut Notch
Logs Split with Axe
Loom and Grass Mats
Lost in the Woods
Map & Compass
Maps: Without Compass
Measurement Estimation
Menu Worksheet
Menu (Adult IOLS)
Night Tracking
Old Trails
Pioneering, Basic
Pioneering Models
Plaster Casts
Rope Care
Rope Making
Rope Spinning
Scout Reports
Signal & Sign
Sign Language
Silent Scout Signals
Smoke Prints
Spanish Windlass
Staff/Stave Making
Stalking Skills
Stalking & Observation
Story Telling
Stoves & Lanterns
Summoning Help
Sun Dial: Scientific
Survival Kit
Tarp Poles
Teepee (4 Pole)
Tent Care
Tent Pitching
Tomahawk Throwing
Tomahawk Targets
Totem Making
Totem Animals
Totem Poles
Training in Tracking
Tracks, Ground, Weather
Tracking & Trailing
Trail Following
Trail Signs & Blazes
Trail Signs of Direction
Trail Signs: Traditional
Trail Signs for Help
Trees of the NE
Wall Hangings
Watch Compass
Weather Wisdom
Wild Things

Scout Books

Site Contents

by Ernest Thompson Seton 

The spacing can best be done by actually registering the course of the sun's shadow during the entire day, making sure that the pointer is constantly pointed to the north.

More scientific ways of ascertaining the angles between the lines may be used if desired; for instance, such as are given on page 81 of Professor Jacoby's Astronomy or in the Encyclopedia Britannica.

However, there is no necessity for those living in the latitude of New York City to use any of the above methods, as the following angles have been worked out and tested and will be found to be approximately correct:

Between Hr. 12 Noon and Hrs.   1  or 11 10 degrees
       "         Hrs. 1 & 2    " 11 & 10 11   
       "           "       2 & 3   " 10 & 9 12 1/2  
       "           "       3 & 4   " 9 & 8 15
       "           "       4 & 5   " 8 & 7 19
       "           "       5 & 6   " 7 & 6 22 1/2
 Total from 12 to 6 (1/4 the circle) 90 degrees

The angle between hrs. 6 and 7 P. M. (likewise between 5 and 6 A.M.) is also 22 1/2 degrees, as the night hour-lines are prolongations of the day hour-lines.

For boys and girls who might have difficulty in determining angles by degrees, the following thumb rule for the locality of New York City will be found useful:

Have the quarter circle from 12 to 6 o'clock divided into six unequal parts, the smallest sector being next to 12 o'clock and the other sectors uniformly increasing in size so that the largest is next to 6 o'clock. The smallest angle should be 1/9 of the quarter circle, and the largest angle should be about 1/4 the quarter circle.

Bear in mind that the entire dial must be symmetrical in two ways; that is, the A. M. and P. M. halves of the dial are symmetrical, also the day-time and night-time halves are symmetrical (insofar as the sun shores before 6 A. M. and after 6 P. M.). This double symmetry is true in any latitude or longitude; hence the importance of affixing the pointer at the center of the dial, its upper edge meeting the surface of the dial on the straight line extending across from 6 A. M. to 6 P. M.

When the dial has been constructed by any of the above methods, put it in the sun and do not be surprised if it does not register the same time as common clock time. It will probably be a few minutes ahead or behind it even if accurately made, as for astronomical reasons too complex for explanation here the sun is irregular in its apparent movements. To ascertain our railroad time there would have to be convenient to hand the following memorandum:

Dec. 23d Dial Correct. 
Feb. 15th Dial Slow 15 minutes. 
April 15th Dial Correct. 
May 15th Dial Fast 4 minutes. 
June 15th Dial Correct.
Aug. 1st Dial Slow 6 minutes.
Sept. 1st Dial Correct. 
Nov. 1st Dial Fast 16 minutes.

A further allowance would have to be made if the location does not happen to be on the standard meridian from which clock or railroad time is taken. For instance, New York City lies one degree east of the standard meridian for Eastern time, hence a further adjustment would have to be made due to the fact that the sun is thus 4 minutes faster than it would be on the exact meridian. The variation of any other locality can be calculated similarly, allowing 4 minutes fast for each degree the place lies east of its standard meridian; similarly the dial will be slow if its locality is west of its meridian.

If the hour-lines are originally laid out on the dial by the practical process of noting the movement of the sun's shadow hour by hour, then it is preferable either that this be done at one of the times during the year when sun-time and clock time are approximately identical or that proper allowance computed from the above table be made; otherwise it is easy to see that a variation from clock time rising at times to a maximum of half an hour might result.

Another point which is added for the sake of completeness rather than its importance, is the variation between morning and afternoon time caused by the width of the sun itself, as it covers half a degree in the sky. The light from preceding edge of the sun is in the morning a minute ahead of what it would be were the sun but a point in the sky. Likewise the light lags a minute behind in the afternoon. These trivial variations can of course be disregarded.

Caution: Do not attempt to locate the north by following rally a magnetic needle. In New York City the needle points ten degrees to the west of the real north. Moreover, a compass is apt to be affected by surrounding iron or steel objects such as a steam radiator. The north pole is a much more accurate guide although it at times varies a degree from the true north. For the information of those living in New York City it is convenient to know that the up and down avenues of the city (such as Fifth Avenue and Amsterdam Avenue) point east of north at an angle of about 30 degrees. 

It is better to have the pointer as thin as possible, as if has any substantial thickness the eastern and western halves of the dial markings will have to be separated by that width. This is because the sun registers with one edge in the morning and the other edge in the afternoon. Also do not forget that it is always the side of the shadow cast by the upper side of the pointer which is to be regarded in noting the time.

Sun dials are an ornament to any garden. New York residents can find one quietly at work in the flower gardens at Van Cortlandt Park. Chronic pessimists would do well to ponder the inscription on King Edward's sun dial:

"Let others tell of rains and showers, 
I only record the sunny hours."


To make a more scientifically accurate Sundial, see Collins Book of the Stars.

See Also:

Simple Indian Clock, Shadow Clock, or Sundial 

The Birch Bark Roll 






Additional Information:

Peer- Level Topic Links:
Activities ] Archery ] Axe, Boy Scout ] Axe, Saw, Forestry ] Axe, Saw,  Knife ] Axe Use: Beard ] Axe Use: Seton ] Axe Use: Traditional ] Axe Throwing ] Beds, Woodcraft ] Bedding Materials ] Bicycle Maintenance ] Birch-Bark Torch ] Birds ] Bird Houses ] Blocks Tackles Purchase ] Blood Red Cross ] Broom: Camp or Witch's ] Buttons ] Campcraft ] Camp Hygiene ] Camp Planning ] Campfire Programs ] Catapult ] Chainsaws ] Checklists ] Chuck Box Riddance! ] City-Craft ] Compass Bear Song ] Compass, Home-Made ] Cooking ] Cotton Kills Bear Song ] Deduction in Tracking ] Deduction & Detective ] Drum ] Dyes ] Edible Plants ] Equipment, Leader ] Equipment, Personal ] Equipment Maintenance ] Equipment, Lightweight ] Equip, Pickle Bucket Camp ] Estimation ] Field Signals ] Fire-Building ] Fire Building ] Fire Laying ] Fire Lighting ] Fire Starters ] Fire: Rubbing-Stick ] Fire Types, Wood Types ] Fire Council Ring ] Fires: Woodcraft ] First Aid ] First Class Journey ] Flint & Steel ] Flowers ] Forest ] Gesture Signals ] Ground to Air Signals ] Handicraft Stunts ] High Adventure ] Hiking ] Hike Planning ] Indian Sundial Clock ] Insect Collecting ] Insect Preserve ] Indian Well ] Knife & Hatchet ] Knots, Bends, Hitches ] Knots: Diamond Hitch ] Knots: Lashings ] Knots: Rope Work ] Knots: Seton ] Knots: Traditional ] Knots & Whipping ] Lashings ] Lashing Practice Box ] Lace or Thong ] Learn by Doing ] Leave No Trace ] Leave No Trace ] Lights ] Local Knowledge ] Log Ladders, Notched ] Log-Rolling ] Logs: Cut Notch ] Logs Split with Axe ] Loom and Grass Mats ] Lost in the Woods ] Manners ] Maps ] Map & Compass ] Maps: Without Compass ] Measurement ] Measurement Estimation ] Menu Worksheet ] Menu (Adult IOLS) ] Mosquitoes ] Mushrooms ] Night Tracking ] Observation ] Old Trails ] Paints ] Pioneering, Basic ] Pioneering Models ] Plaster Casts ] Preparations ] Proverbs ] Rake ] Rope Care ] Rope Making ] Rope Spinning ] Scout Reports ] Signal & Sign ] Sign Language ] Silent Scout Signals ] Smoke Prints ] Snakes ] Spanish Windlass ] Spoons ] Staff/Stave Making ] Stalking Skills ] Stalking & Observation ] Stars ] Stools ] Story Telling ] Stoves & Lanterns ] Summoning Help ] [ Sun Dial: Scientific ] Survival Kit ] Tarp Poles ] Teepee (4 Pole) ] Tent Care ] Tent Pitching ] Tom-Tom ] Tomahawk Throwing ] Tomahawk Targets ] Totem Making ] Totem Animals ] Totem Poles ] Training in Tracking ] Tracks, Ground, Weather ] Tracking & Trailing ] Trail Following ] Trail Signs & Blazes ] Trail Signs of Direction ] Trail Signs: Traditional ] Trail Signs for Help ] Trees of the NE ] Wall Hangings ] Watch Compass ] Weather Wisdom ] Wild Things ]

Parent- Level Topic Links:
Scuba ] Skills ] Games ] Shelter ] Fire ] Night ] B-P's Camping ] Hikes ] Indian ] Spring ] Summer ] Autumn ] Winter ]

The Inquiry Net Main Topic Links:
 [Outdoor Skills]  [Patrol Method [Old-School]  [Adults [Advancement]  [Ideals]  [Leadership]  [Uniforms]

Search This Site:

Search Amazon.Com:

When you place an order with Amazon.Com using the search box below, a small referral fee is returned to The Inquiry Net to help defer the expense of keeping us online.  Thank you for your consideration!



Amazon Logo



Scout Books Trading Post

Dead Bugs, Blow Guns, Sharp Knives, & Snakes:
What More Could A Boy Want?

Old School Scouting:
What to Do, and How to Do It!

To Email me, replace "(at)" below with "@"

If you have questions about one of my 2,000 pages here, you must send me the "URL" of the page!
This "URL" is sometimes called the "Address" and it is usually found in a little box near the top of your screen.  Most URLs start with the letters "http://"

The Kudu Net is a backup "mirror" of The Inquiry Net.  

2003, 2011 The Inquiry Net,  In addition to any Copyright still held by the original authors, the Scans, Optical Character Recognition, extensive Editing,  and HTML Coding on this Website are the property of the Webmaster.   My work may be used by individuals for non-commercial, non-web-based activities, such as Scouting, research, teaching, and personal use so long as this copyright statement and a URL to my material is included in the text
The purpose of this Website is to provide access  to hard to find, out-of-print documents.  Much of the content has been edited to be of practical use in today's world and is not intended as historical preservation.   I will be happy to provide scans of specific short passages in the original documents for people involved in academic research.  


Last modified: October 15, 2016.