Here is a map of the Russian Empire of the late 18th century and I want to know its projection system. Unfortunately, the map does not contain information, which latitude point is a basis/which coordinate system it uses.
Could you give me an advice, how to transform the unknown projection of the map into a commonly used ones (e.g. WGS84). I can georeference the raster but it is not a solution in my case because I need to know how to transform the values of the system for other maps, which use (apparently) the same projection system. Examples of the rasters to transform using the projection are below.
P.S. Updated a second link. Should work now.