if (document.images) {            

  // In Images

             		 	 img1on = new Image();      

            img1on.src = "images/enviro_on.jpg";

           		 	     img2on = new Image();      

            img2on.src = "images/tactical_on.jpg";
			
           		 	     img3on = new Image();      

            img3on.src = "images/proj_on.jpg";
			
           		 	     img4on = new Image();      

            img4on.src = "images/pub_on.jpg";





  // Out Images

           		 	     img1off = new Image();      

            img1off.src = "images/enviro_off.jpg";

                       	 img2off = new Image();      

            img2off.src = "images/tactical_off.jpg";
			
                       	 img3off = new Image();      

            img3off.src = "images/proj_off.jpg";
			
                       	 img4off = new Image();      

            img4off.src = "images/pub_off.jpg";



        }



// Function to 'activate' images.

function imgOn(imgName) {

        if (document.images) {

            document[imgName].src = eval(imgName + "on.src");

        }

}



// Function to 'deactivate' images.

function imgOff(imgName) {

        if (document.images) {

            document[imgName].src = eval(imgName + "off.src");

        }

}