var dufftravelURL = "imgs/dufftravel1.jpg";

if (document.images) {
     var dufftravel1 = new Image();
     dufftravel1.src = "imgs/dufftravel1.jpg";

     var dufftravel2 = new Image();
     dufftravel2.src = "imgs/dufftravel2.jpg";
	 
	 var dufftravel3 = new Image();
	 dufftravel3.src = "imgs/dufftravel3.jpg";
	 
}

function changeDufftravel() {
     if (document.images) {
        if (dufftravelURL == "imgs/dufftravel1.jpg") dufftravelURL = "imgs/dufftravel2.jpg";
		else if (dufftravelURL == "imgs/dufftravel2.jpg") dufftravelURL = "imgs/dufftravel3.jpg";
		
         document.myDufftravel.src = dufftravelURL;
	}
}