You may have a mouth ulcer if you have: 1  A painful sore or sores inside your mouth, on the tongue, soft palate (the back portion of the roof of your mouth), or inside your cheeks. 2  Sores in your mouth that are round, white, or grey in colour, with a red edge or border.
Perpetually moving minecart track. Works underwater and above. Upvote this! http://redd.it/m9zrx. If you are using this for survival, make sure you have air bubbles along the way (such as signs) so you can breath. Song: Rainy Day in Paris: http://www.newgrounds.com/audio/liste...
How does a phoropter work (mechanically)? There seem to be some really neat gear/clutch mechanisms at work throughout the device, what are the actual mechanisms involved? For instance, how does the axis adjustment knob adjust all the astigmatic lenses and the cross cylinder at the same time? Or how does the fast sphere knob work?