multiplying glass

noun2

1. •
   A glass with a number of facets, causing an object to appear multiplied many times.

   • It may have one side, which must be convex, ground into little facets, like those of some jewels, while the other side is plain. Children know it by the name of a multiplying glass […] — 1776
2. •
   (no longer used) A magnifying glass.

   • poring through a multiplying glasse, / Vpon a captiu’d crab-louse, or a cheese-mite / To be dissected, as the sports of nature, / With a neat Spanish needle — 1631