The Mars Signal Light Co. also built warning lights for police & fire equipment. For many years Los Angeles County F.D. specified a Mars self - contained single lens oscillating red light, either above the windshield or on the hood, on their fire apparatus.
The Fall 2009 issue of S-P Trainline magazine, has an excellent article on " The Light from Mars ", which explains its' applications on Espee locomotives. I still remember well, the sight of Espee freights climbing Tehachapi in the evening, with the signal light playing peek - a - boo along the hills. Really freaky was the time an Eastbound had a Rio Grande tunnel motor on the point, with its' figure 8 signal light on.
Also remember that Northern Pacific used a red Gyralight, and Frisco a WHITE Gyralight, as an additional light on the nose of some of their freight diesels.