Why are my older post so small?

My front page or “home” page will hold 2 post at most. When I update the front page with a new post the older post rolls over. The problem I have is the older post on the following pages show up very small unlike the way they originally were on the front page. If you scroll down to the bottom of my website http://www.thegreypelican.com/ and click “Next Page” it will show you the small images unlike the larger ones in the front. How do I fix this?