if (document.images) {

home_on = new Image();
home_on.src="buttons/home_roll.gif";
home_on.alt="Home";
about_on = new Image();
about_on.src="buttons/about_roll.gif";
about_on.alt="About the CSR";
mission_on = new Image();
mission_on.src="buttons/mission_roll.gif";
mission_on.alt="EPO Mission Statement";
projects_on = new Image();
projects_on.src="buttons/projects_roll.gif";
projects_on.alt="EPO Projects";
hete_on = new Image();
hete_on.src="buttons/hete_roll.gif";
hete_on.alt="HETE EPO Program";
people_on = new Image();
people_on.src="buttons/people_roll.gif";
people_on.alt="EPO People";
partners_on = new Image();
partners_on.src="buttons/partners_roll.gif";
partners_on.alt="EPO Partners";
press_on = new Image();
press_on.src="buttons/press_roll.gif";
press_on.alt="Astronomy Press and News";
education_on = new Image();
education_on.src="buttons/education_roll.gif";
education_on.alt="Educational Resources for K-12 Teachers";
tour_on = new Image();
tour_on.src="buttons/tour_roll.gif";
tour_on.alt="Tour Info and Signup";
feedback_on = new Image();
feedback_on.src="buttons/feedback_roll.gif";
feedback_on.alt="Feedback and Questions";

home_off = new Image();
home_off.src="buttons/home.gif";
home_off.alt="Home";
about_off = new Image();
about_off.src="buttons/about.gif";
about_off.alt="About the CSR";
mission_off = new Image();
mission_off.src="buttons/mission.gif";
mission_off.alt="EPO Mission Statement";
projects_off = new Image();
projects_off.src="buttons/projects.gif";
projects_off.alt="EPO Projects";
hete_off = new Image();
hete_off.src="buttons/hete.gif";
hete_off.alt="HETE EPO Program";
people_off = new Image();
people_off.src="buttons/people.gif";
people_off.alt="People";
partners_off = new Image();
partners_off.src="buttons/partners.gif";
partners_off.alt="Partners";
press_off = new Image();
press_off.src="buttons/press.gif";
press_off.alt="Press and News";
education_off = new Image();
education_off.src="buttons/education.gif";
education_off.alt="Educational Resources";
tour_off = new Image();
tour_off.src="buttons/tour.gif";
tour_off.alt="Tour Info and Signup";
feedback_off = new Image();
feedback_off.src="buttons/feedback.gif";
feedback_off.alt="Feedback";
}

function changeImages(imgname,img) {
  if (document.images) {
      document[imgname].src = eval(img + ".src");
      document[imgname].alt = eval(img + ".alt");
  }
}