var x = 0
	var mainpic = new Array();

mainpic[0] = new Image();
mainpic[0].src = 'gfxhist/main1.jpg';

mainpic[1] = new Image();
mainpic[1].src = 'gfxhist/main2.jpg';

mainpic[2] = new Image();
mainpic[2].src = 'gfxhist/main3.jpg';

mainpic[3] = new Image();
mainpic[3].src = 'gfxhist/main4.jpg';

mainpic[4] = new Image();
mainpic[4].src = 'gfxhist/main5.jpg';

mainpic[5] = new Image();
mainpic[5].src = 'gfxhist/main6.jpg';

	function setImageDisplay()
	{
		var picBeingShown = document.getElementById("mainDisplay");
		picBeingShown.src = mainpic[x].src;
	}

	function setFirstGrey()
	{
		var firstButtonGreyed = document.getElementById("firstButton");
		firstButtonGreyed.style.color="#999999";
		firstButtonGreyed.style.cursor="default";
	}

	function setFirstUngrey()
	{
		var firstButtonUngreyed = document.getElementById("firstButton");
		firstButtonUngreyed.style.color="#669999";
		firstButtonUngreyed.style.cursor="pointer";
	}

	function setPreviousGrey()
	{
		var previousButtonGreyed = document.getElementById("previousButton");
		previousButtonGreyed.style.color="#999999";
		previousButtonGreyed.style.cursor="default";
	}

	function setPreviousUngrey()
	{
		var previousButtonUngreyed = document.getElementById("previousButton");
		previousButtonUngreyed.style.color="#669999";
		previousButtonUngreyed.style.cursor="pointer";
	}

	function setNextGrey()
	{
		var nextButtonGreyed = document.getElementById("nextButton");
		nextButtonGreyed.style.color="#999999";
		nextButtonGreyed.style.cursor="default";
	}

	function setNextUngrey()
	{
		var nextButtonUngreyed = document.getElementById("nextButton");
		nextButtonUngreyed.style.color="#669999";
		nextButtonUngreyed.style.cursor="pointer";
	}

	function setLastGrey()
	{
		var lastButtonGreyed = document.getElementById("lastButton");
		lastButtonGreyed.style.color="#999999";
		lastButtonGreyed.style.cursor="default";
	}

	function setLastUngrey()
	{
		var lastButtonUngreyed = document.getElementById("lastButton");
		lastButtonUngreyed.style.color="#669999";
		lastButtonUngreyed.style.cursor="pointer";
	}

	function setPicNumber()
	{
		var picNumber = x+1;
		document.getElementById("picNo").innerHTML=" "+picNumber+" of 6";
	}

	function setCaption()
	{
		if (x==0)
			{
			document.getElementById("picturecaption").innerHTML="Repertor deep-laden alongside Customs House Quay in Ipswich Dock — still with full sailing rig";
			}
		else if (x==1)
			{
			document.getElementById("picturecaption").innerHTML="Repertor sailing light — probably why the photographer crew member had time to go out to the end of the bowsprit";
			}
		else if (x==2)
			{
			document.getElementById("picturecaption").innerHTML="Repertor in Ipswich Dock in the 1930s giving her hard-working but cheerful crew a well-earned break";
			}
		else if (x==3)
			{
			document.getElementById("picturecaption").innerHTML="Repertor taken from the air in almost a flat calm in the Thames Estuary — laden and fully rigged";
			}
		else if (x==4)
			{
			document.getElementById("picturecaption").innerHTML="Repertor deep-laden, under power with reduced rig — no bowsprit, no mizzen, but a wheelhouse";
			}
		else if (x==5)
			{
			document.getElementById("picturecaption").innerHTML="Final days in trade — Repertor converted to be a motor tanker carrying acid from London to Brantham";
			}
	}

	function firstImage()
	{
		x = 0
		setImageDisplay();
		setFirstGrey();
		setPreviousGrey();
		setNextUngrey();
		setLastUngrey();
		setPicNumber();
		setCaption()
	}
	
	
	function previousImage()
	{
		x--
		if (x<0)
			{
			x = 0
			}
		else if (x==0)
			{
			setFirstGrey();
			setPreviousGrey();
			}
		else if (x==4)
			{
			setNextUngrey();
			setLastUngrey();
			}
		setImageDisplay();
		setPicNumber();
		setCaption()
	}
	
	
	function nextImage()
	{
		x++
		if (x>5)
			{
			x = 5
			}
		else if (x==5)
			{
			setNextGrey();
			setLastGrey();
			}
		else if (x==1)
			{
			setFirstUngrey();
			setPreviousUngrey();
			}
		setImageDisplay();
		setPicNumber();
		setCaption()
	}
	
	
	function lastImage()
	{
		x = 5
		setImageDisplay();
		setFirstUngrey();
		setPreviousUngrey();
		setNextGrey();
		setLastGrey();
		setPicNumber();
		setCaption()
	}