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Subjects
- Education--United States--History--19th century.2
- Geometry--Early works to 1800.2
- Navigation--Early works to 1800.2
- Railroads--United States.2
- Sailing ships.2
- Surveying--Study and teaching.2
- Trigonometry--Early works to 1800.2
- Trigonometry.2
- Agricultural laborers--Pennsylvania.1
- Agriculture--Pennsylvania.1
- Air pilots--United States.1
- Aircraft industry--United States.1
- Algebra--Early works to 1800.1
- Algebra--Study and teaching.1
- Angles (Geometry)1
- Animals.1
- Apples--Harvesting.1
- Artillery.1
- Brakes.1
- Brickmaking.1