Invention and Engineering
A ballpoint pen is a pen that dispenses ink (usually in paste form) over a hard ball rolling in its point. The materials commonly used are steel, brass, or tungsten carbide. The design was conceived and developed as a cleaner and more reliable alternative to dip pens and fountain pens. It is now the world's most-used writing instrument, with millions manufactured and sold daily. It has influenced art and graphic design and spawned an artwork genre.
Boone and Scenic Valley Railroad 8419.
History of the LED.
Text from Wikipedia; plate via Wikimedia Commons. Text CC BY-SA 4.0; plate freely licensed (see Commons). Source record. Images and catalogue data are reproduced from open-access collections.