Dissected Triangular Prism, Ross Solid #9

This is the ninth in a series of models illustrating the volume of solids designed by William Wallace Ross, a school superintendent and mathematics teacher in Fremont, Ohio. The unpainted wooden model is a triangular prism with three rectangular sides and a triangular base and top. It separates into three pyramids of equal volume; two of these are identical. A diagram of the dissection appears on one of two paper stickers glued to the model. A mark on one label reads: Triangular Pris [. . .].
Finding the volume of pyramids was not only important for practical reasons but was central to Ross’s demonstrations for the volume of a cone and of a sphere.
For Ross solids, see 1985.0112.205 through 2012.0112.217. For further information about Ross models, including references, see 1985.0112.191.
Currently not on view
Object Name
geometric model
date made
ca 1895
Ross, W. W.
Physical Description
wood (overall material)
overall: 15.5 cm x 7.5 cm x 7.5 cm; 6 3/32 in x 2 15/16 in x 2 15/16 in
place made
United States: Ohio, Fremont
ID Number
catalog number
accession number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Arithmetic Teaching
Data Source
National Museum of American History, Kenneth E. Behring Center


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