if (document.images) {
scienceoff = new Image
historyoff = new Image
popoff = new Image
childrenoff = new Image
holidayoff = new Image
foodoff = new Image
contactoff = new Image

scienceon = new Image
historyon = new Image
popon = new Image
childrenon = new Image
holidayon = new Image
foodon = new Image
contacton = new Image

scienceoff.src = "images/nav_science.jpg"
historyoff.src = "images/nav_history.jpg"
popoff.src = "images/nav_pop.jpg"
childrenoff.src = "images/nav_children.jpg"
holidayoff.src = "images/nav_holiday.jpg"
foodoff.src = "images/nav_food.jpg"
contactoff.src = "images/logo_contact.jpg"

scienceon.src = "images/nav_science_r.jpg"
historyon.src = "images/nav_history_r.jpg"
popon.src = "images/nav_pop_r.jpg"
childrenon.src = "images/nav_children_r.jpg"
holidayon.src = "images/nav_holiday_r.jpg"
foodon.src = "images/nav_food_r.jpg"
contacton.src = "images/logo_contact_r.jpg"

}
else {

scienceoff =  " "
historyoff =  " "
popoff =  " "
childrenoff =  " "
holidayoff =  " "
foodoff =  " "
contactoff =  " "

scienceon =  " "
historyon =  " "
popon =  " "
childrenon =  " "
holidayon =  " "
foodon =  " "
contacton =  " "

document.science =  " "
document.history =  " "
document.pop =  " "
document.children =  " "
document.holiday =  " "
document.food =  " "
document.contact =  " "

}