Making a simple refracting telescope

 To make a simple telescope, two cardboard tubes will be needed, one fitting inside the other.  It is not possible to make a satisfactory telescope unless good lenses are available, a fact which was soon discovered by early experimenters.

A linen tester (sometimes a stamp magnifier also) has lenses which are achromatic, that is corrected for colour distortion. Like lens of focal length 2 or 3 cm will provide a suitable eye-piece when mounted in a cork with a hole in it.