function AddPrestige()
{
   var ss = SpreadsheetApp.getActiveSpreadsheet();
   var calculatorSheet = ss.getSheetByName("Calculators");
   var proressTrackerSheet = ss.getSheetByName("Progress Tracker");

   var column = proressTrackerSheet.getRange('I:I');
   var values = column.getValues(); // get all data in one call
   var emptyRowIndex = 0;
   while ( values[emptyRowIndex][0] != "" )
   {
     emptyRowIndex++;
   }

   var dateCellName = ('I' + (emptyRowIndex + 1));
   var dateCell = proressTrackerSheet.getRange(dateCellName);

   var timeCellName = ('J' + (emptyRowIndex + 1));
   var timeCell = proressTrackerSheet.getRange(timeCellName);

   var bookOfShadowsCellName = ('L' + (emptyRowIndex + 1));
   var bookOfShadowsCell = proressTrackerSheet.getRange(bookOfShadowsCellName);

   var d = new Date();
   var dateString = d.toDateString();
   var timeString = d.toLocaleTimeString('en-GB');

   // Remove 'GMT' or equivelent
   var index = timeString.indexOf(" ");
   timeString = timeString.substring(0, index);

   dateCell.setValue(dateString);
   timeCell.setValue(timeString);

   var bookOfShadowsLevel = calculatorSheet.getRange('Q48').getDisplayValue();
   bookOfShadowsCell.setValue(bookOfShadowsLevel);
}