Coulter Counter-Model A

In 1949, Wallace H. Coulter discovered a method for detecting and counting particles suspended in a fluid medium, later named the Coulter principle. Forcing a particle-filled fluid through a small aperture in an electrical current modulated the current, allowing Coulter to count the number of particles in the fluid. Coulter patented his Coulter Counter in patent number 2,656,508, a “Means for Counting Particles Suspended in a Fluid” on October 20, 1953, with an improvement filed in 1956 that added a manometer to move a precise volume of fluid through an aperture. In 1958, Wallace and Joseph Coulter established Coulter Electronics, Inc. to pursue commercial applications of their Coulter Counter. This Coulter Counter Model A was used during the 1970s and 1980s at the Animal Care Facility at the University of California, San Francisco. The Coulter Counter has a wide range of applications in medicine and science, most importantly in determining red and white blood cell counts.
date made
ca 1973
Coulter Electronics, Inc.
Coulter, Wallace H.
Physical Description
metal (overall material)
glass (overall material)
plastic (overall material)
electronics (overall material)
overall: 50.7 cm x 41 cm x 24.5 cm; 19 15/16 in x 16 1/8 in x 9 5/8 in
ID Number
catalog number
accession number
Credit Line
Gift of University of California Medical Center, Animal Care Facility (through Joseph Spinelli, D.V.M.)
See more items in
Medicine and Science: Medicine
Health & Medicine
American Enterprise
American Enterprise
Exhibition Location
National Museum of American History
Data Source
National Museum of American History


Add a comment about this object