Alain A gnomon that projects an image onto the inside of a cylindrical shape is not too difficult to do. This is quite similar to a gnomon that projects an image onto the inside of a sphere. In both cases the natural location of the gnomon is at that center of curvature of the cylinder or sphere.
If your design calls for projection of an image onto the outside of a cylinder then the basic question is, where do you place the gnomon. If it is placed close to the cylinder then the cylinder may be approximate by a plane to get some idea of the hour lines. The problem is that the hour lines would be small and hard to see. If the gnomon is placed further away from the cylinder, say at a great distance, then only the noon hour could be read. So the question remains, where do you place the gnomon. When that is decided, and the radius of curvature of the cylinder is known, the projection of hour lines or analemmas can be carried out. I would enjoy such a task. Dan Wenger >Hi, all diallists ! > >Writing from France (this to please you excusing my "under-basic >English" !:-)), I have the same problem than Alexei Pace : > >I'm asked to realise a vertical sundial on a circular tower. I don't >know exactly (it's a truism !) how to proceed. >This sundial will probably be built on stone, but we can't curve the >stone. Then I think that it will be possible to realise like a multiface >dial. >What does the sundial list think about such a challenge ? >Completely crazy or just a half ? > >Best regards >(under the falling rain in Alsace :-(( > > >Alain MORY > > >Alexei Pace a écrit: >> >> Hello >> >> If you design a vertical south dial , and 'wrap' it around a south facing >> gnomon on a cylinder,,, will it work? >> >> I would like to know how one may design a sundial on say a cylindrical >> building....you cannot simply turn the building around like as in a >> cylindrical/sheperd's dial! >> The one at Disney was of this form... but I dont knwo what type of dial >>is that >> >> thanks for any help >> >> alexei pace Daniel Lee Wenger Santa Cruz, CA [EMAIL PROTECTED] http://wengersundial.com http://wengersundial.com/wengerfamily
