Consider caching your element selectors like this:
var $image = $('#my-div img');
This way jQuery doesn't have to traverse the DOM more than once to select the element.
Also, I believe you can do all of your mousedown() event code in one block.
Edit: oops, upon further inspection, I see you are doing this all in the console. Caching the selector is still possible, but now I understand why you did the mousedown() event the way you did.
var $image = $('#my-div img');
This way jQuery doesn't have to traverse the DOM more than once to select the element.
Also, I believe you can do all of your mousedown() event code in one block.
Edit: oops, upon further inspection, I see you are doing this all in the console. Caching the selector is still possible, but now I understand why you did the mousedown() event the way you did.