A simple sundial for everyone

One of my goals for the cabin is to have an example of each of the major types of sundials somewhere on site.  During a recent trip, I experiemented with a layout for a reflected ceiling dial inside the house.   It didn’t work well in the living room because of the vigas (not a flat surface), but the sunroon looked promising.

As explained in Sundials: Their Theory and Construction, “A mirror placed horizontally in a southern window will reflect a beam of sunlight to the ceiling of the room.  As the sun moves across the sky from east to west, the reflected sunbeam moves across the ceiling from west to east; and if hour lines are properly drawn upon the ceiling, the sunbeam can be used to tell the time of day or even day of the year.”    

Because there is a low roof overhang preventing solar gain in the summer (to keep the house cool), this sundial will only work when the sun is lower in the sky, late fall through early spring.  The sunroom is very narrow, so the sunbeam falls along the wall, not up on the ceiling.  The plaster is a natural mud plaster, so I’m thinking I’ll calculate the meridian lines and place small stones in the mud to mark the hours.  It will take some time to make the calculations and check their accuracy.  We’ll have to watch, mark, and recheck for a year to be sure.

As you can see in the photos, the beam of light is quite bright, and during this visit, we actually had fun guessing the time by the placement of the light.  Lots of jokes about the time being “window thirty” or “half past the pipe”.

a tiny mirror makes the dial

If you want to try making your own dial, it isn't difficult.  You will have to polish your geometry skills, but the projects are straightforward. Sundials: Their Theory and Construction by Albert E. Waugh is my favorite book about making dials.  It's out of print, but still available through Amazon.  Try looking for it at your library.