It would take a lot of typing to fully answer the metallurgical control question. Suffice it to say that the primary alloying & adjusting elements were Carbon, Silicon, Manganese, and chrome. "Base" iron was melted and the alloy composition was adjusted in the hot metal cranes as they were filled from the holding furnaces (in front of the cupolas). Further adjustments were made at the individual molding lines. There were only two basic types of iron. Blocks & drums required a higher chrome for wear and/or tensile (class 30 iron). Carbon, silicon, and chrome were further adjusted at the mold lines (as the metal was poured into the pouring ladles) for additional strength, and casting feeding requirements. Gray iron producers were cupola melters back then, so Manganese was used to "tie up" excess sulfur in the iron. Foundry metallurgy was essentially controlled/analyzed by eutectometers (carbon & silicon analysis via cooling curve) and chill samlpes (carbide tendency). The full lab with spectrometer, Leco, wet lab, and mechanical testing was located at the forge (next door to the foundry) - connected via pneumatic transport tube. Believe me - that's the "cliffs notes" version!