Sundial slides

Summary
a) The location of the temporary plaque, next to the stairs, has worked well for almost one-and-a-half years Slide 1.
b) A larger, more visible location, in the sunlight, would be a plaque or plaques on the concrete sidewalk blocks just behind the stairs, in front of the gnomon and the marble plaque Slide 1a
c) A proposed location on the north side of the gnomon has several shortcomings: 1) the plaque is always in the shade 2) on a sunny day, the sun will hit you in your eyes as you try to read it Slide 4 3) the long, narrow format is not as easy to read as the more common rectangular formats seen in Slide 1 and Slide 1a
d)  Finally, if a plaque were mounted, or vandalized, on a 108 year old concrete gnomon, the gnomon could be damaged and the accuracy of the sundial ruined. This would be very difficult or impossible to repair.
Concrete benches in Sundial Park have needed replacement, other concrete benches along Ashton Avenue are missing or broken.

These slides should be viewed on a large screen.

Slide 1
1

In June, 2020, I found that the 1914 Sundial booklet said that there was a plaque at the Ingleside Terraces Sundial. The plaque had been missing for many years. I put together a temporary plaque and we installed it at the entrance to the Sundial to the left of the stairs.

This is the main entrance to the sundial, as it is the only location with stairs and sidewalk blocks, which lead to the 1913 marble plaque and the gnomon. A larger plaque, or plaques on either side of the stairs, could be installed.

According to the 1914 Sundial booklet, page 9, "There are several entrances to the sundial park in Ingleside Terraces, but by far the best way to view the spot in all its beauty is from the entrance to the south".

Slide 1a
1.a.
Just behind the stairs are four concrete sections, each measuring 2 feet x 2 feet. There is space for ground level plaques, similar to the Hollywood Walk of Fame or the Castro Rainbow Honor Walk.
The accompanying photo shows this proposed location, with a plaque on the left to be used for historical information, and a 17"x14" plaque on the right used for the table giving the minutes to be added or deducted from sundial time to obtain local time. Larger plaques could be installed if needed.
Right click and use the (+) sign for a larger image (the photo of the chart has an orange streak that occurred in the printing).


1921 plaque in the brick sidewalk at 1st and Market, San Francisco.
Right click and use Ctrl+ for a larger image.

Slide 2
2

This is the sundial chart that we developed.
It has several user friendly features. The times are arranged in two minute intervals, so that the time adjustment can always be read within a minute, which is the limit of accuracy for a sundial.
Numerical data is from NOAA

It gives instructions on how to use the chart and how to read the Ingleside Terraces sundial.

There is information about the sundial. The San Francisco Landmark number will be added.

Slide 3
3

For comparison, here is a plaque from New Zealand.
It is a nice plaque, but it doesn't contain as much information as our plaque.

It has the typical Equation of Time chart. The time adjustments are shown three times a month, which creates odd intervals.
For example, in February, three different days have the same time adjustment. But there are other dates that have a four, five, or six minute gap, which makes it more difficult to attempt to read the time adjustment to the nearest minute.

Slide 4
4

Here is a proposed location on the north side of the gnomon.

A plaque on the north side of the gnomon would be in the shade (unretouched photo with a sample printout of an 8"x30" plaque). If you come by in the middle of the day, which is the best time to read a sundial, the sun will hit you in your eyes as you attempt to read the sundial plaque.

A 8"x30" plaque is narrow and tall, would extend from approximately 4 feet to 6.5 feet above ground level, and be more difficult to use than the 17"x14" plaque in Slide 1.a., although both plaques are very close in size (240 vs. 238 square inches). Right click and use the (+) sign for a larger image.

Standing at this location, you are blocking other people from reading sundial time.

The original plaque in this location has probably been missing for 80 to 90 years. Its exact content is unknown.

Slide 5
5

I have a website with many pages about sundials. Several of my webpages are ranked very highly on Google.
As you can see in the recent screenshots, my webpage on sundial plaques ranked number one in a Google search for that topic, out of 623,000 results, and my webpage on sundial accuracy ranked number two, out of more than eight million results(!).
Google searches 10/9/2021 on a PC

Slide 6
6
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Our Ingleside Terraces sundial is a working,
surprisingly accurate sundial, not just an historical artefact.
We want a plaque that will best serve another generation.

A permanent sundial plaque should be placed next to the stairs or in the concrete sidewalk blocks behind the stairs, see Slide 1 and Slide 1a, as these locations are at the entrance to the sundial, are most visible, are in the sunlight, do not interfere with users of the sundial, and there is room for user friendly, informative plaques.

Creative Commons License
Robert Karis
www.sfog.us

Alphabetical index
Extreme sundials
Geographic north
Ingleside Terraces Sundial
Ingleside Terraces Sundial accuracy
Sundial factoids
Sundial plaques
Sundials EOT tables