var num=0;

imgArray = [
  ['images/Investigations/Invest20081213_01.JPG','Thrown Magnet','1/11 - Thrown Magnet'],
  ['images/Investigations/Invest20081213_02.JPG','Light Anomaly','2/11 - Light Anomaly'],
  ['images/Investigations/Invest20081213_03.JPG','Light Anomaly','3/11 - Light Anomaly'],
  ['images/Investigations/Invest20081213_04.JPG','Multiple Light Anomalies','4/11 - Multiple Light Anomalies'],
  ['images/Investigations/Invest20081213_05.JPG','Light Anomaly','5/11 - Light Anomaly'],
  ['images/Investigations/Invest20081213_06.JPG','Multiple Light Anomalies','6/11 - Multiple Light Anomalies'],
  ['images/Investigations/Invest20081213_07.JPG','Light Anomaly','7/11 - Light Anomaly'],
  ['images/Investigations/Invest20081213_08.JPG','Light Anomaly','8/11 - Light Anomaly'],
  ['images/Investigations/Invest20081213_09.JPG','Multiple Light Anomalies','9/11 - Multiple Light Anomalies'],
  ['images/Investigations/Invest20081213_10.JPG','Light Anomaly','10/11 - Light Anomaly'],
  ['images/Investigations/Invest20081213_11.JPG','Multiple Light Anomalies','11/11 - Multiple Light Anomalies']
]

function slideshow(slide_num) {
  document.getElementById('mypic').src=imgArray[slide_num][0];
  document.getElementById('mypic').alt=imgArray[slide_num][1];
  document.getElementById('burns').innerHTML=imgArray[slide_num][2];
}

function slideshowUp() {
  num++;
  num = num % imgArray.length;
  slideshow(num);
}

function slideshowBack() {
  num--;
  if (num < 0) {num=imgArray.length-1;}
  num = num % imgArray.length;
  slideshow(num);
}