Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Category_Science Gifts two adjustment screws on a

two adjustment screws on a spring-loaded aluminum bar

This round convex glass mirror is designed for physics and educational uses

9A with oxidized constantan winding on a vitreous-enameled steel tube and a phosphor-bronze sliding contact

Built for vacuum filtration

providing the cleanest hand-operated way to make and break a circuit during early electricity instruction with stackable modules

Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Category_Science Gifts two adjustment screws on aOptically worked double concave glass lens at 75mm diameter and 150mm focal length, the diverging curvature producing virtual upright images for refraction and beam spreading work.