var lat1; 
var lon1; 
var lat2; 
var lon2; 


function drawMap(){

document.getElementById("imgDisplay").src ="http://www2.demis.nl/wms/wms.asp?wms=WorldMap&VERSION=1.1.1&REQUEST=GetMap&SRS=EPSG:4326&Layers=Bathymetry,Countries,Topography,Hillshading,Builtup%20areas,Coastlines,Waterbodies,Inundated,Rivers,Streams,Railroads,Highways,Roads,Trails,Borders,Cities,Settlements,Spot%20elevations,Airports,Ocean%20features&BBOX="+lon1+","+lat1+","+lon2+","+lat2+"&SRS=EPSG:4326&&WIDTH=620&HEIGHT=620&FORMAT=image/png&BGCOLOR=0xffffff&TRANSPARENT=TRUE&EXCEPTIONS=application/vnd.ogc.se_inimage&";

}