function preload_sf() {
if(document.images) {
  var ImgArray = new Array();
  for (var i = 0; i < 16; i++) {
    ImgArray[i] = new Image();
  }    
	ImgArray[1].src = "../sfeature/images/sf_nations_popn_1850_over.gif";
	ImgArray[2].src = "../sfeature/images/sf_nations_popn_1860_over.gif";
	ImgArray[3].src = "../sfeature/images/sf_nations_popn_1870_over.gif";
	ImgArray[4].src = "../sfeature/images/sf_nations_popn_1880_over.gif";
	ImgArray[5].src = "../sfeature/images/sf_nations_popn_1890_over.gif";
	ImgArray[6].src = "../sfeature/images/sf_nations_popn_1900_over.gif";
	ImgArray[7].src = "../sfeature/images/sf_nations_popn_1910_over.gif";
	ImgArray[8].src = "../sfeature/images/sf_nations_popn_1920_over.gif";
	ImgArray[9].src = "../sfeature/images/sf_nations_popn_1930_over.gif";
	ImgArray[10].src = "../sfeature/images/sf_nations_popn_1940_over.gif";
	ImgArray[11].src = "../sfeature/images/sf_nations_popn_1950_over.gif";
	ImgArray[12].src = "../sfeature/images/sf_nations_popn_1960_over.gif";
	ImgArray[13].src = "../sfeature/images/sf_nations_popn_1970_over.gif";
	ImgArray[14].src = "../sfeature/images/sf_nations_popn_1980_over.gif";
	ImgArray[15].src = "../sfeature/images/sf_nations_popn_1990_over.gif";
  }
}


/*
";
	ImgArray[1].src = "
*/