--- Begin Forwarded Message --- Date: Tue, 4 May 1999 11:58:59 -0700 From: Jenny Stone <[log in to unmask]> Subject: Fw: polyconic projection Sender: Jenny Stone <[log in to unmask]> Greetings. I've got a stumper of a question about USGS historic maps, quoted below. I can find details on the polyconic projection, as well as the equations used to calculate the meridian, etc., but I can't find the actual parameters that were used by USGS in Washington during that time. Does anyone have any ideas where I might find that? Thanks. Jenny Stone ___________________________________ GIS Librarian * Map Collection University of Washington Libraries Box 352900 * Seattle, WA 98195-2900 phone: 206.543.9392 -----Original Message----- Subject: polyconic projection |Jenne, |I have a question for you related to digitizing a paper map. The map I am |digitizing is a 1898 USGS landcover map. It has a lat/long graticule for |reference coordinates. Based on the date I am assuming the map used the |Clarke 1866 spheroid and the polyconic projection. I am also assuming a |local datum, although it is possible it is connected to one of the earlier |American datums. From looking at Arc/Info help it seems that I need the |datum for the map and parameters for the map such as central meridian, |parallel of origin, false northing and false easting. Do you know if this |information is available and/or whether it is necessary. Thanks for any |help you can provide. --- End Forwarded Message ---