Glenville State University Professor Creates Tool for Land Surveyors
Fri Jan 13, 2023
Glenville State University Lecturer of Land Surveying, Jacob Petry, holds a copy of his invention – the Pathfinder: Directional Conversion Wheel. (GSU Photo/Kristen Cosner)

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GLENVILLE, WV – The concept of geomagnetic secular variation – a gradual change to Earth’s magnetic field – is often tricky for surveying students to understand. However, its importance to boundary location is paramount as it affects magnetic compass bearings over time. Historically, surveyors used compass observations as a basis for beginning boundary surveys. An individual who follows in the footsteps of the original surveyor would observe a different magnetic bearing today.
“I remember being told as a student that it was no reflection on our ability to learn, but some of us would understand secular change, and some wouldn’t – I fell into the second category. Then, after spending several hours working mathematical computations and trying to visualize two magnetic norths that varied slightly, the idea for the directional conversion tool appeared,” said Jacob Petry, a Lecturer of Land Surveying at Glenville State University.
Petry realized that his invention – the Pathfinder – not only helped him but would also help other students and field professionals alike.
After a few months of conceptualizing the idea with his brother Kaleb, an Army pilot and expert land navigator familiar with circular slide rules, they created a prototype and filed a provisional patent application with the United States Patent and Trademark Office.

The Pathfinder was recently sold to Builder’s Book, Inc., a California-based company specializing in educational materials for surveyors and engineers.

Builder’s Book is now selling the Pathfinder: Directional Conversion Wheel on their website.

They advertise the Pathfinder as a “simple analog tool” that “streamlines the reconnaissance process” for surveyors. The product information also notes that it is a helpful tool for student surveyors as it simplifies the understanding of secular variation without the need for advanced tools or specialized training.

“I’m proud of the Pathfinder, and seeing it on the market brings me joy. I believe aspiring land surveyors will receive as much help out of it as I have,” Petry added.
He is graduating with a Master of Science in Engineering Technology with a concentration in Surveying Engineering Technology from the University of Maine this spring.

The Pathfinder can be purchased online by visiting