World War 2 era searchlight

After my visit to Ft. MacArthur in San Pedro I'm again looking into the earliest use of carbon arc searchlights by the U.S. Army. I know that the Army had 6 portable searchlight sets on order at the beginning of the Spanish American War. These consisted of two horse drawn wagons, that appear to be modified fire fighting apparatus. This idea is confirmed by a photograph of the generator set mounted on a steam fire engine, similar to apparatus built by American La France. I found these photos in the Army handbook c.1900 " for the use of electricians, in the operation and care of Electrical Machinery and Apparatus of the U.S. Seacoast Defences" photos to follow later. Sometime later, after 1904 the Army switched to a gas engine to supply power to the 36' searchlight.