San Lorenzo Valley Museum is counting on locals to visit its newest exhibition, “The Way We Calculated,” at the San Lorenzo Valley’s Faye G. Belardi Memorial Gallery in Felton. The exhibition runs until June 15, with a reception on Saturday, March 15, from 2-4pm.
This exhibition features a plethora of artifacts and archives, most of which have never before been exhibited: devices to calculate board feet of lumber; adding machines used in local business; ledgers and inventories; and voting and population data. Topics explored include: methods of counting and measuring; precision versus accuracy; notation and hand-writing; and mathematical tables used in schoolrooms to surveyor offices that were created by human computers.
Also on exhibition is a model of Vannevar Bush’s 1931 differential analyzer—a mechanical analog computer that solves differential equations. Educators teaching calculus can arrange a private demonstration for their students by contacting the Museum.
Laura DeAngelis, executive director of the SLV Museum, explained how temporary exhibitions are brought to fruition.
“Sometimes they are curated internally, such as this upcoming one, sometimes they are traveling exhibitions, such as one later in 2025 entitled ‘Telling Stories of Mexican California: Real Life & Myth Making.’ In these cases, we add to the exhibition additional local stories,” DeAngelis said. “Sometimes they are curated in partnership with another entity, such as the ‘Birth Happens’ exhibition curated in partnership with two midwives, and ‘From Footpaths to the Superhighway—How Connections Shaped Scotts Valley’ curated with the Scotts Valley Historical Society. Sometimes they are curated entirely by another entity, such as ‘Look | Act | Inspire,’ an exhibition by the UCSC Ken Norris Center.”
In 2026, SLV Museum will be one of just three institutions in California chosen to host “The Road I Call Home,” which features photographic portraits and stories of the homeless from the lens of multi-award winning photographer and humanitarian Randy Bacon.
“We do try to host one community exhibition per year, usually over the holiday period, in which the public is given a theme and they provide the objects, such as ‘Transport of Delight,’ ‘Playing with History’ or ‘Fabric and Fiber,’ to name a few,” DeAngelis said. “The curator then builds the exhibition around those objects.”
While museum staff welcome all to visit their displays, “The Way We Calculated” is especially relevant to students of all ages.
“There is something about seeing a problem being solved mechanically that is very riveting. The model of the differential analyzer has been exhibited at the Vintage Computer Festival four times, each time winning awards, such as Best in Show and the People’s Choice Award, most recently in 2023,” DeAngelis said. “Demonstrations of the working machine will be given every weekend that the exhibition is open and also by special request. We are hoping that educators teaching calculus will arrange a private demonstration for their students.”
In addition, DeAngelis sees this exhibition as a way to understand the history of calculations—not just how they’ve been done in years past, but also as a way to appreciate the current methods of working with numbers.
“We are using these objects and archives as a window into the lives of those that used them—people mind power—and into occupations that no longer exist, such as human computers, clerks, time keepers and operators, and how much some occupations have changed. There will be quite a few hands-on objects, especially for younger visitors (abacus, calipers, adding machines, scales and an addition ruler),” DeAngelis said.
The Faye G. Belardi Memorial Gallery in Felton is located at 6299 Gushee St. For more information, visit slvmuseum.org.
