[Engineering drawing: Gates Rock and Ore Breaker / Gates Iron Works, Chicago. Drawn by A.H. Alexander, 11 Nov 1887. Line drawing with wash, scale 3" : 1'. Accompanied by promotional booklet (40p., Dec. 1888 edition), and a sheet (32 x 47cm.) bearing an engraved sectional perspective view and a lengthy ts. explanation. The actual rock and ore breaker, inv. no. 1891-218, was disposed of in ca.1930]