1. Man vs machine chart, comparing effectiness of 2nd new method, includes operations Collection: Early 20th Century Engineering Lantern Slides Set: Merit Rating Date: undated Format: Image Agent: unknown
2. Man vs. machine chart, comparing effectiveness of new method, includes operations Collection: Early 20th Century Engineering Lantern Slides Set: Merit Rating Date: undated Format: Image Agent: unknown
3. Man vs. machine chart, comparing effectivness of old method of spooling plaster includes operations. Collection: Early 20th Century Engineering Lantern Slides Set: Merit Rating Date: undated Format: Image Agent: unknown
