If you are seeing unexpected results from the measurement tool, check that your map units are set correctly. The map units are either decimal degrees, feet, or meters. In ArcIMS Author or ArcExplorer—Java Edition, the map units can be set from the View menu by selecting Scale Bar Properties>Map Units. The map units can be set for the ArcIMS Viewers using the Scale Bar panel in ArcIMS Designer.
When measuring distances in ArcExplorer—Java Edition, if the data is in decimal degrees, the measurements will be inaccurate. The farther from the equator, the more inaccurate the measurements will be. The reason for this is that there is no use of a projection engine within the current version of ArcExplorer—Java Edition. Therefore, all measurements are approximate when using decimal degrees.