Optically Worked Double Convex Glass Lens, 75mm Diameter, 250mm Focal Length Included_Bosshead allowing this tangent galvanometer to

allowing this tangent galvanometer to convert deflection angle into an absolute current reading

Glass-flask leaf electroscope with a brass rod and aluminum leaf

The hBAR infrared thermometer is perfect for remotely measuring the temperature of objects

Solid glass friction rod that develops a positive electrostatic charge when rubbed with silk or wool

Optically Worked Double Convex Glass Lens, 75mm Diameter, 250mm Focal Length Included_Bosshead allowing this tangent galvanometer toLong focal double convex glass lens at 75mm diameter and 250mm focal length, the f 3. 3 geometry stretching focal throw for distant screen projection of well formed real images.