Trust the bar scale only because it was designed to represent the nominal scale of the map. If a world map, then the scale is true at the equator. Your method of measuring at random points is not a good idea unless the map projection is equidistant--and only works along the central meridian and equator. On Fri, May 18, 2018 at 11:55 AM, Rick Grapes <[log in to unmask]> wrote: > Hi all, > > > > I have a calculating scale question. This map I’m cataloging has a bar > scale. I measured the bar, did the math, and got the ratio. > > > > Just for the fun of it I also measured between 2 points on the map, as far > apart as the map would allow, obviously much greater than the bar scale, > then measured between the same 2 points on google maps, and again did the > math. The difference was about 10%. Which calculation would you trust? > Granted, either entries in the 255 would be an approximation. A potential > issue could be divergent projections etc. Any suggestions? > > > > Rick Grapes > > BYU Map Cataloger > -- Maureen Kelley, PhD Lecturer, Geography & Global Studies Department San Jose State University