2009-01-222009-01-221903-08Indiana State Board of Health. Monthly Bulletin. 1903; 5(8) :90.0019-6754https://hdl.handle.net/1805/1764[Chalkboard erasers before and after, using Chalk dust cleaner]Fujitsu fi-4220c2, Adobe Photoshop CS3, 966 KBPage 90, lower left approximately 5 X 2 in.Photograph in periodical.JPEGen-usErasersIndianaChalkDustInventionsJones, J.A.(Plymouth)SchoolsSimple MachinesBaskets of dusty and clean chalboard erasers demonstrate the Chalkdust cleaner invention.Image