Northern sundials (both vertically mounted and horizontal versions) need to be pointed North, whereas Southern sundials need to be pointed South. The article is stating that Southern horizontal versions can be mounted vertically in the Nothern hemisphere but must be pointed South.
I hope that helps, I had to re-read it a few times, myself.
Northern sundials (both vertically mounted and horizontal versions) need to be pointed North, whereas Southern sundials need to be pointed South. The article is stating that Southern horizontal versions can be mounted vertically in the Nothern hemisphere but must be pointed South. I hope that helps, I had to re-read it a few times, myself.