The idea is to monitor for control many tanks of changing volumes to monitor and to be quickly able to see tank level with telescope or binoculars without making constant trips between each tank. Light color and place within the color range would be enough monitor control.
We have large storage tanks with mechanical gauges (the rectangle with horizontal ground marker) and the added lamp is connected to this indicator. The large square over light and pointer is clear plastic with three color bands of translucent paint to let light behind show through in a different color. Probably best to attach power cord to plastic square to take weight of cord off mechanical indicator yet allow enough cord for full mechanical gauge movement.
A few paragraphs could explain this to farmers and workers with little formal education in the 1930's. If CAD conversion is needed to understand this you should consider asking for a refund or suing the college.
