Glass is liquid while it’s hot. At 1,100 °C it glows orange and moves like honey, and a glassblower keeps turning the pipe so it doesn’t drip.
This lens is a gather of glass that never sets. It settles on the line you’re reading and magnifies it, and it stays cool while you read. Heat it and the rim glows, the air above it shimmers, and a quick pull stretches it. Leave it and it cools back to clear glass.
A glassblower works soda-lime glass between 900 and 1,100 °C. It softens at about 720 °C.