tripson = new Image();   tripson.src="buttons/trips.jpg";
    photoson = new Image();  photoson.src="buttons/photos.jpg";
    writingson = new Image();  writingson.src="buttons/contact.jpg";
    researchon = new Image();   researchon.src="buttons/research.jpg";


    function mOver(imgId,imgName) {
       document.images[imgId].src = imgName;
    }

    function mOut(imgId,imgName) {
       document.images[imgId].src = imgName;
    }