wp_enqueue_script not loading my custom js file

I am using the following code below in my functions.php, However app.js is not found when I inspect it in the resources tab.

It is looking for it in http://localhost:8888/goodMorningMoon/javascripts/app.js?ver=3.3.1

when it should be looking in http://localhost:8888/goodMorningMoon/wp-content/themes/Good-Morning-Moon/javascripts/app.js?ver=3.3.1

How do I modify this code so it looks in the correct directory, do I need to add get_template_directory_uri(); somewhere, I have tried but to no avail.

Thanks in Advance

p.s this is located in my functions.php file, since I read from here http://smashingshare.com/2010/09/22/how-to-properly-add-javascript-files-to-your-wordpress-site/ that that is the proper way to approach including js files.

<?php
function load_scripts() {
   wp_enqueue_script('jquery');
   wp_enqueue_script('my_javascript_file', '/javascripts/app.js', array('jquery'));
}    

add_action('init', 'load_scripts');
?>