Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Category_Science Gifts Rotary-knob resistance substitution board offering

Rotary-knob resistance substitution board offering twelve discrete values from 33 ohms to 10M ohms with 4mm lead connections

Sturdier-than-glass metal displacement vessel at 100 by 50mm with a side spout

Natural gas Tirrill Bunsen burner pairing a gas flow valve with air flow adjustment for finer flame control

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

Square-topped wooden screw simple-machine model with a leverage block

Optically Worked Double Concave Glass Lens, 75mm Diameter, 150mm Focal Length Category_Science Gifts Rotary-knob resistance substitution board offeringOptically 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.