The Boy Mechanic, vol. 1, page 338
Take a piece of very clear ice and melt it down into the hollow of your hands so as to form a large lens. The illustration shows how this is done. With the lens-shaped ice used in the same manner as a reading glass to direct the sun's rays on paper or shavings you can start a fire. - Contributed by Arthur E. Joerin.
“Finally, brothers, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable – if anything is excellent or praiseworthy – think about such things.”
– Philippians 4:8