When Francis C. Moon came to Cornell University in 1975 as a professor
of engineering mechanics, he had no idea that priceless treasures
lay half forgotten in the school’s closets. Over time, Moon learned
that a historic collection of 230 mechanical models—the largest surviving
collection of Reuleaux models—were hidden away in neglected storage
areas, dusty cabinets, and even a boathouse.
The Reuleaux models were the brainchild of the 19th-century German
engineering professor, Franz Reuleaux (1829-1905), who was known for
his theories on kinematics—the science of pure motion. As part of
a systematic study of basic mechanical building blocks, Reuleaux designed
and built more than 800 different models, each embodying a basic machine
element. He used the models for research and as a teaching tool, and
in the 1870s he authorized the German manufacturer Gustav Voigt, Mechanische
Werkstatt, to reproduce 350 of them so that they could be used to
teach engineering students throughout Germany and around the world.
“When I first came to Cornell, I didn’t know about this collection,”
Moon recalls. “But then I got a letter from somebody in Berlin looking
to buy the collection, so I knew I was on to something.”
With a little detective work, Moon learned that in 1882, Cornell’s
president, Andrew Dickson White, used an $8,000 donation to procure
more than 250 of the models. Within 75 years, the investment would
prove to be priceless. The majority of the models made from Reuleaux’s
design stayed in Berlin, where they were destroyed during World War
II. Collections in St. Petersburg, Russia, and at Montreal’s McGill
University have also been lost, making Cornell’s the largest known
collection of kinematic models designed by the founder of modern kinematics.
As a land grant university, Cornell needed a curriculum in the “mechanical
arts,” and the Reuleaux collection was meant to equip the mechanical
engineering department with teaching tools that combined mathematical
fundamentals and practical, hands-on learning. Reuleaux himself supervised
the models’ shipment to Ithaca.
Although they had once been the prized possession of the department,
the Reuleaux models eventually fell out of favor. Students came to
the university with more than enough hands-on mechanical engineering
experience, having tinkered with farming equipment, automobiles, and
other machines as youngsters. Kinematics fell out of fashion as an
independent engineering course by the 1960s. Engineers still learned
kinematics as part of coursework in dynamics, and more often than
not, the subject was taught using mathematics rather than models.
As is inevitably the case with most wonders of a bygone era, the Reuleaux
collection was packed away in old wooden cabinets in Cornell’s computer
science department, largely forgotten by the school’s mechanical engineers.
When Moon found out about the Reuleaux collection, he says that “most
of the models were in a state of benign neglect. They hadn’t been
used, but they hadn’t really deteriorated either.” Even after 120
years, all but one of the brass and cast iron models show no rust
and all but six are still in good working order. This remarkable resilience,
Moon says, can be credited to Reuleaux. He understood that working
with the models would be a tactile experience for students; they would
want to handle them and make them move. So he created the models’
cast iron with an alloy that would be rust resistant.
Along with the Reuleaux models, Moon unearthed a number of fascinating
other mechanisms. One of the first motorized calculating machines,
known as “The Millionaire,” was found in a janitor’s closet at Cornell.
Perhaps no one has benefited from the rediscovered kinematic models
more than Cornell’s engineering students. Moon and several other faculty
members at Cornell routinely use the devices as teaching tools. In
the electronic age, youngsters just don’t tinker with machines the
way that they once did, Moon says, and using the machines helps them
gain a sense of three-dimensionality: “As soon as you see the models
doing something you want to know why.”
Moon, along with his colleague Hod Lipson, designed a lesson he calls
“Leonardo in your toothbrush” as part of a sophomore design synthesis
course. Students get an inexpensive electric toothbrush to take apart
and analyze in terms of the models in the Reuleaux collection. One
of the models they use is the Slider-Crank model—a mechanism that
converts rotary motion into alternating linear motion. The slider-crank
is one of the most ubiquitous mechanisms in the world today. Its design
can be traced back to the drawings of Leonardo da Vinci. So the students
have an opportunity to draw links between the history of engineering
and modern engineering design. “When you look at these machines, each
model embodies a different track of history,” Moon says.
Cornell’s engineering students can’t seem to learn enough about the
Reuleaux collection. “One of our problems is that now students are
banging on the door trying to get to use the models,” Moon jokes.
Because of their immense popularity, he has set aside one week during
the year for students to tinker with the devices.
And the models haven’t been of interest just to engineers. Cornell’s
mathematics and architecture faculty find them fascinating. The chair
of the sculpture department at the Rhode Island School of Design sees
them as works of art and thinks they would be useful for teaching
kinetic sculpture. And Moon says that “local high school teachers
love these models.”
Naturally, the popularity of the priceless collection poses a problem
for Cornell. How can students and educators make the most use of the
models without running the risk of damaging them? John M. Saylor,
director of Cornell’s engineering and computer science library, had
Working with Moon, several members of Cornell’s mechanical engineering
and mathematics faculty, and a handful of dedicated staff and students,
Saylor is spearheading an effort to create a digital library of kinematic
models that will be available on the Internet as part of the National
Science Digital Library. The group won a $725,088 grant from the National
Science Foundation for the project.
Known as the Kinematic Models for Design Digital Library, or K-MODDL,
the digital library will feature the Reuleaux collection along with
Cornell’s other kinematic models. Free via the Web, Saylor says K-MODDL
should be up and running by the end of June at http://kmoddl.library.
cornell.edu. Until then, eager visitors can visit the Web site for
a taste of the projects, and Saylor will present a talk about K-MODDL
at ASEE’s 2004 annual conference in Salt Lake City.
K-MODDL will feature photographs of each mechanism accompanied by
a description of how the model works, the theory and history behind
its design, and, in most cases, an example of a machine that incorporated
the mechanism. The library will also include resources such as historic
engineering texts, literature on kinematics and Reuleaux, and teaching
modules that demonstrate how the models might be used in the classroom
at the undergraduate, high school, and middle school level.
Saylor says that because “the models are really meant for moving
and for people to handle them,” it was important to give K-MODDL’s
visitors more than just a still-life catalog of kinematic devices.
So, each model will also be captured in a movie that users can control
with a computer mouse. Move the mouse from left to right and the model
operates in one direction; move it from right to left and the model
operates in the opposite direction. The speed with which it moves
depends upon how quickly the user moves the mouse.
But the K-MODDL team also wanted to give people an even deeper understanding
of how the models work. “We were really looking to find an edge over
conventional libraries that just offer pictures, movies, and text,”
says Hod Lipson, a professor of mechanical engineering and computer
and information scientist who is one of the project’s collaborators.
Reuleaux designed many of his mechanisms so that they could be taken
apart and put back together in different ways to see how their changes
affected the mechanism. By adding moveable virtual models to the library,
K-MODDL’s developers hope to offer a similar experience.
“You can take the machines apart or modify them,” Lipson says of
the virtual models. “Doing so really allows you to play with it and
explore a lot more of the design space. The interaction lets you ask
‘What if?’ questions. For students, the ability to experiment with
machines and get immediate feedback is very important. When I studied
kinematics it was through equations, and you had to visualize the
motions through equations. Sometimes we saw simulations, but they
weren’t interactive. What we have now allows you to do this in real
Even with all that can be learned from the movies and interactive
virtual models, the K-MODDL team recognizes that experiencing the
Reuleaux collection in two dimensions has its limitations. So they
created a feature that will let visitors to the site make their own
Reuleaux collection using 3-D printing files.
Three-dimensional printing is often used to make plastic prototypes
in order to get an idea of what a product will feel like. “We thought
that we could harness this type of technology to bridge a gap between
the digital Web abstraction and the material world,” Lipson says.
Although the printers cost as much as $100,000, the prices have been
decreasing and the printers are becoming more commonplace at universities.
Individual printouts can be purchased from a printing service. Lipson
says the printed plastic Reuleaux models look and function in the
same way as the originals, they’re just made of different material.
“We can recreate the lost models; we can duplicate existing models.
We can duplicate models from around the world to complete a single
collection,” he says. “This really opens up the possibility for …
more access to the collection than would have been available before.”
Ultimately, the group hopes K-MODDL will spark an interest in the
workings and history of kinematics and engineering among engineers
and students as well as the public at large. “Having it on the Web
really allows people to simply see the machine, grab it, push and
pull it, and see the experiment. Anyone can use it without any prior
knowledge,” Lipson says.
“Most people could benefit from using models of any kind. I think
it helps your abstract thinking even if you’re not going to be an
experimentalist or an engineer,” Moon adds. “Our goal is to present
this collection to the entire world.”
Bethany Halford is a freelance writer based in Baltimore