Sloping sundials (also called sloping shadow clocks) are a type of sundial only found in ancient Egypt. They possibly emerged as a development of the L-shaped sundial, and had the advantage of being more compact. However, their shape has a natural weak point between the gnomon block and the beginning of the slope, with the result that many examples are incomplete.
Objects
In this database, we have included information about five complete instruments:
SS EMC JE 41789: Sloping Sundial JE 41789 in Cairo
SS EMC JE 42927: Sloping Sundial JE 42927 in Cairo
SS Fitz E.GA.4596.1943: Sloping Sundial E.GA.4596.1943 in Cambridge
SS Louvre E 11558: Sloping Sundial E 11558 in Paris
SS Qantara: Sloping Sundial from Qantara
eight sloping parts (the gnomon has broken away):
SS EMC JE 67342: Sloping Sundial JE 67342 in Cairo
SS Florence 14501: Sloping Sundial 14501 in Florence
SS Louvre E 11737: Sloping Sundial E 11737 in Paris
SS MMA 12.181.307: Sloping Sundial MMA 12.181.307 in New York
SS MRAH E.07303: Sloping Sundial E.07303 in Brussels
SS Paris: Sloping Sundial in Paris
SS Petrie UC16376: Sloping Sundial UC16376 in London
SS Vatican 55462: Sloping Sundial MV 55462 in the Vatican
and three gnomons:
SS Berlin ÄM 22824: Sloping Sundial Gnomon ÄM 22824 in Berlin
SS BM EA74841: Sloping Sundial Gnomon EA74841 in London
SS Turin 7353: Sloping Sundial Gnomon 7353 in Turin
Characteristics
The characteristics of sloping sundials are:
- Fixing for a plumb bob: usually the top face and/or sides of the gnomon display small holes which could be plumb bob attachment points
- Reference line for plumb bob: a vertical line on one or both sides of the gnomon, used to align the plumb bob thread in order to keep the instrument level.
- For timekeeping, only the length (and not the direction) of the shadow is considered.
- Flat (linear) shadow-casting edge: more familiar types of sundial use a pointer or even a hole.
- Flat, sloped shadow-catching surface: the surface is tilted at an angle to the bottom of the sundial.
- Hour marks: circles, holes, or lines marking lengths long the scale from the gnomon outwards. The marks get further apart the further away from the gnomon.
- Month lines: the hour marks are arranged along line running the length of the sloping surface, parallell with the sides of the sundial.
- Month labels: each month line is labelled with the name of one or two month names.
Characteristics 1-4 are shared with L-shaped sundials. Many examples are missing one or more of characteristics 6-8. This could be because of missing parts (e.g. an inlay made of another material that was originally fixed to the sloping surface), an unfinished state of manufacture, or the object was intended as a model of a sundial (used as a votive offering) rather than a functional timekeeping device. Indeed, it is possible that all the sloping sundials that survived to be described so far were intended as votive offerings.