I Need to Get an Adapter

It took me a good while to explain what I wanted, which they did not have at the Office Depot. They thought I wanted to buy laptop adapter, but what I need is something which would allow me to use a hard drive with my tablet. I have a couple of small pocket sized hard drives which are powered by USB, so it seems like they should work on my Samsung Galaxy Tab 4, but they are not recognized. I have this adapter which should work and it will do just fine with a thumb drive. I can use the 8 gigabyte thumb drives that I have, but that is only enough for one or maybe two High Definition movies. I am thinking that I can put all the movies, TV shows and music that I could reasonably need on that Western Digital portable 1 TB hard drive. I can probably tape it to the back of the tablet really, although I am not sure that would be a good idea to be honest. At any rate I am wondering if there is a limit to how much power you can draw off of the tablet, or perhaps it does not really produce much power for external devices like hard drives. I need to figure out if it is possible or not. You can buy really big USB drives, but they are really expensive. In fact I see one that is a really good deal compared to the others, but the others cost pretty much the same as what I paid for my terabyte hard drives. Obviously those are four times as big as those. Of course if I had a couple of them that would serve the same purpose, but I already have the hard drives and so I would like to use them