Despite the fact that there were no clean, unscratched lenses on
the island, there is a very simple microscope you can make using
a tiny (about 2mm diameter) ball of glass. To get lenses of high quality,
the spherical balls need to stay small. The reason why the glass
beads are spherical instead of tear-drop shaped is due to surface
tension. With small enough blobs of melted glass, the force
of surface tension keeps the balls round. Once the balls get too
big, gravity starts to deform the spheres into drop shapes.
It is essential that you wear eye protection when using a flame
and working with glass.