Sundials have been used as timepieces for many centuries , with an unchanged basic functional design . A sundial consists of the flat airplane where the fourth dimension section are stigmatise , and the gnomon , which is the raised part that cast a shadower to determine the clock time . A right position sundial will be a middling accurate horologe as well as a cosmetic addition to your garden . commend , a sundial tells you sun time and not clock time . On a sundial , noonday is always when the sun is straight overhead . The remainder of the time segments are separate accord to the sun ’s way of life across the sky , which changes seasonally .
Step 1
Prepare a strong stand or reenforcement to hold your sundial . Once you have the sundial set correctly , it should remain immovable .
Step 2
Place the sundial so the length of the blade of the gnomon is aligned with the earth ’s bloc of rotation , which is true north . True north is not precisely the same as magnetic Frederick North , which is the pull of a orbit acerate leaf toward the North Pole , but a compass is closemouthed enough for a garden sundial .
Step 3
apply a plumb occupation to mold a true vertical to indicate noontide . advert a plumb object from a string about 5 feet long . When it casts no shadow , rotate your sundial on its pedestal until there is no shadow on the sundial plane .
Step 4
line up the angle of the gnomon to correspond with your parallel of latitude . For truth , the angle of the gnomon must be the same as your slant of latitude . For example , if a gnomon has a 33 degree angle , and your latitude is 38 degree , it will not be accurate for your arena . Use a protractor to correct the angle by tilting the sundial plane 5 degrees , and wedge it solidly in station . The gnomon will then be angled at 38 degrees .
Tip
Seasonal dispute occur due to the earthly concern ’s tilt ( long or shorter day distance ) , and these differences will vary according to your latitude . genuine noon , when the Sunday is directly overhead , varies one stage of longitude every four minutes . This is because the movement of the sun across the sky is 15 degrees westward per hour .
