Smithsonian museums continue to be closed to support the effort to contain the spread of COVID-19. Read a message from our director, and check our website and social media for updates.

Holometer of Brunel

Holometer of Brunel

<< >>
Usage conditions apply
This instrument has a black wooden case painted to resemble a book. On the inside is a paper scale in the shape of an octant (eighth of a circle), screwed to the case, with the center of the circle at the front left corner. A metal arm that pivots on this center has a plastic indicator at the opposite end. Scales lettered from A to N that are marked near the circumference. The scales represent tangents, cotangents, sines, cosines, the division of an arc of a circle into differing numbers of equal parts, lengths of the sides and areas of inscribed polygons, areas of the faces and volumes of inscribed polyhedra, and proportions of ellipses. Across the bottom edge are two linear scales, one of centimeters divided to millimeters and one of inches divided to lines (twelve lines/inch).
The holometer was an invention of the French nobleman Louis-Clément de Brunel de Varennes who spent many of his formative years fighting Napoleon’s army. The engraving of the scales was done by Pelicier. Brunel envisioned the instrument as a replacement for the sector, particularly useful in design.
The instrument was noted in contemporary journals but does not seem to have become common.
L.-C. Brunel de Varennes, Métroscopographie, ou Nouveau système de perspective, Paris: Bachelier, 1830.
J. W. Woollgar, “Description of the Holometer,” Mechanics Magazine, vol. 14, September 18, 1830, pp. 40-42.
Currently not on view
Object Name
Calculating Instrument, Trigonometric
date made
ca 1830
Brunel de Varennes, Louis-Clement
Physical Description
wood (case material)
paper (scale material)
metal (arm material)
plastic (indicator material)
overall: 3.6 cm x 45.6 cm x 33.2 cm; 1 13/32 in x 17 15/16 in x 13 1/16 in
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.


Add a comment about this object