IT pocket sundial chart

The Ingleside Terraces Sundial was dedicated on October 10, 1913. The Sundial and its park are San Francisco Landmark #293. The dial is 34 feet in diameter. The gnomon is 28 feet long and 17 feet high.

IT Sundial Chart

Solar noon, XII on the Ingleside Terraces Sundial, occurs when the shadow of the gnomon lies between the two metal rods at XII. Solar noon is halfway between sunrise and sunset. To calculate clock time for solar noon at the summer solstice, for example, on June 21, look at the above chart. 1 hour 12 minutes needs to be added to sundial time to obtain local clock time PDT on June 22; solar noon on June 22 will occur at 1:12 P.M. PDT.    To determine the time for solar noon on June 21, you can do a calculation: two minute time interval in 9 days from June 13 to June 22 = 120 seconds in 9 days = 13 seconds per day, so solar noon will occur 13 seconds earlier on June 21. However, a sundial is only accurate within one or two minutes. An approximation to the nearest minute is close enough; solar noon will occur at 1:12 P.M. PDT on the summer solstice, June 21.

A 4"x6" stainless steel plaque, with a QR code that links to this webpage, is located in front of the curb to the left of the stairs at the entrance to the sundial south of the gnomon. The plaque is very reflective. Stand in front of the plaque to put it in the shade, when you use your cell phone to get the link from the QR code.

IT Sundial charts link to this page.

Internet Archive link to this page.