Sundials have been used to measure time for thousands of years.This simple device can be made up of nothing but a flat dial and a gnomon, but can still be hard to read if you are just starting out.Setting up your sundial correctly and completing a few simple calculations will allow you to know the hour no matter where you are.
Step 1: The sundial should be placed on a flat surface.
When a sundial is on a flat surface, it will work correctly.It will not get knocked down or moved if you place it in a safe spot.
Step 2: Make sure your sundial is in direct sunlight.
It seems obvious, but it is crucial!If you want to be able to read your sundial from dawn to dusk, keep it out in an open, unshaded area.Some sundials won't work for the hours that the sun is not up.
Step 3: If you are in the northern hemisphere, point the gnomon north.
To find true north, use a compass or look for the North Star at night.The gnomon, or the pin of the sundial, is pointing straight north.The 12:00 noon notation will point north as well because it is aligned with the gnomon.
Step 4: If you are in the southern hemisphere, face the gnomon south.
If you live below the equator, you need to point the gnomon of your sundial towards the south.If you look for the Southern Cross constellation, you can find true south and adjust your sundial accordingly.You can find the Southern Cross by looking for 4 stars.The sky will be higher if you are farther south.
Step 5: If you're at the equator, use a vertical sundial.
It is difficult to use a traditional horizontal sundial along the equator due to the angle of the sun.Use a vertical sundial and follow the instructions to set it up.The sun rises along the eastern horizon and sets on the western horizon at the equator.The shadow would fall in the morning and afternoon if you used a horizontal sundial.
Step 6: There is a shadow line on your sundial.
When your sundial is casting a shadow in the sunlight, take a look at it.You can use the shadow's outer edge to read your sundial like a clock.You should split the denotations into even sections so you can get an accurate estimate.
Step 7: Find the center of your time zone.
Depending on your location, your sundial can be off by up to an hour.To fix this, you need to know how many hours you are behind or ahead of the Mean Time.For every hour you are behind, the center of your time zone will be 15 west.Pacific Standard Time is 8 hours behind.If you divide 8 hours by 15 you get 120.You can find the current time using the internet.
Step 8: You can find the distance between your location and the center of your time zone.
You can find your own location by using a gps device.If you want to know if you are to the east or west of your time zone, you have to calculate the distance from your location to your central location.Seattle is at 122.3 West longitude.The central location of the time zone is 120 West, so Seattle is 2.3 miles away.
Step 9: For every degree away from the center, add or subtract four minutes.
To get a more accurate estimation of the time from your sundial, use your calculation.Divide the difference between your latitude and central latitude by 4.Add your answer to the time and subtract it if you live east or west.In Seattle, you would divide 2.3 by 4 to get 9.2.Since Seattle is west of the time zone's center, you need to add 9.2 minutes to make them equal.If your sundial reads that it is 1:45 pm in Seattle, you would have to add 9 minutes.Why 4 minutes?If you divide 60 minutes by 15, you can see that it takes about 4 minutes for the sun to move through 1 degree.
Step 10: If it is Daylight Saving Time, add one hour.
Daylight Saving Time lasts from early spring to mid-fall.You can add an hour to your sundial to match the time on the clock.Daylight Saving Time starts and ends in your region.
Step 11: To find the exact time, calculate the Equation of Time.
Depending on the day, the sundial's time can be different by as much as 15 minutes.If you want the most precise time estimate from your sundial, use an Equation of Time table.Add or subtract from the time if you search online.You have to enter in your year and time zone.The calculator will tell you how to change your sundial time throughout the year.