Optically Worked Double Convex Glass Lens, 75mm Diameter, 100mm Focal Length Entomology & Zoology_Zoology Charts & Models plus a removal tool in

plus a removal tool in a 4-compartment storage box

25mm enameled copper wire on a 355 x 50mm air-cored former with 4mm safety sockets and a 6A maximum

and acrylic in a foam-lined wooden case for density-versus-material investigations

sliding freely through the ring when cool but arrested once flame heating expands the ball beyond fit

Optically Worked Double Convex Glass Lens, 75mm Diameter, 100mm Focal Length Entomology & Zoology_Zoology Charts & Models plus a removal tool inOptically worked double convex glass lens at 75mm diameter and 100mm focal length, the f 1. 3 geometry favoring strong convergence and bright real image formation across a wide aperture.