multiple db connection issue

[eluser]theprodigy[/eluser]
OK, this may be more than one subject, but here goes.....

I am building a module using Matchbox. I need to connect to multiple databases simultaneously. In my model constructor I have

Code:

function MGalleries()
{
    parent::Model();
    $db = $this->load->database('default', TRUE);
    $check = $this->load->database('mine', TRUE);
}

Then, later, I try to use one of them using

Code:

$db->select('...');

but I am receiving an error

A PHP Error was encountered

Severity: Notice

Message: Undefined variable: db

Filename: models/mgalleries.php

Line Number: 12

What am I doing wrong? Is this something wrong with my Matchbox, or am I supposed to call the database loading from a controller and not in the model constructor?

Please help,

Thanks