Classes & 2 Dim Array Help

I need to do some screen scraping and I am playing with a table object.
I would like to iterate through a table in the syntax of $table->tr->td or
$table->tr[$i]->td[$j] I Guess.

The problem is initializing my $td array.
I seem to get erroneous initialization values.

How do I do this simple test properly ?
Can I skip the $td declaration ?
Something seems wrong about that.

Thanks in advance.

#### table object ####

<?
Class Table {

var $tr = array("td" => array());

function testFill() {
$this->tr[0]->td[0] = "col1";
$this->tr[0]->td[1] = "col2";
$this->tr[1]->td[0] = "val1";
$this->tr[1]->td[1] = "val2";
}

function Table () {
$this->testFill();
}

}
?>

#### program ####

<?
include ("class.Table.php");

$table = new Table();

while (list($key,$row) = each($table->tr)) {
echo "$key = " . $row->td[0] . "\n";
echo "$key = " . $row->td[1] . "\n";
}
?>

#### erroneous output #########

td =
td =
0 = col1
0 = col2
1 = val1
1 = val2