dattier@jolnet.orpk.il.us (David W. Tamkin) (10/16/89)
John R. Levine contributed to issue 450, volume 9: | The V&H tape uses some other projection that I expect is intended to | make equal distances equal. Intended, perhaps, but not successful. A projection that makes equal distances on the earth's surface equal on a plane map is impossible unless the area being mapped is a mesa top. As long as the distances between points are to be calculated as Pythagorean diagonals, something has to break down somewhere. My guess is that the coordinates are based on many projections of small areas; there would still be a problem in joining these smaller maps, but perhaps the theory is that with greater distances the error is less significant as rate bands become larger and fewer. With Illinois Bell, though, the coordinates are gospel: there is an eight-mile band for local calls, and the Chicago-Irving and Schiller Park CO's are a few feet more than eight miles apart. Illinois Bell dutifully charges a call between those two districts in the eight-to-fifteen mile band. On the other hand, the Chicago-Canal East and Chicago-Canal West switches, being in the same building, have the same coordinates assigned, so the distance between them never comes into consideration, though it is perhaps almost as great as the excess over eight miles in the distance between the Schiller Park and Chicago-Irving switches. David W. Tamkin dattier@jolnet.orpk.il.us {attctc,netsys}!jolnet!dattier P. O. Box 813 Rosemont, Illinois 60018-0813 (708) 518-6769 (312) 693-0591 BIX: dattier GEnie: D.W.TAMKIN CIS: 73720,1570 The opinions above are mine.