Screw Loose

Sometimes you just know that you have a screw loose, but sometimes it’s not until after that you’ve been squinting at the screen for some time wondering why you can’t focus today.  At least you wish you had noticed that you had had a screw loose because you find the left hand lens of your glasses lying in the glasses case . . .
 
Even more annoying when you hear the tinkle of the screw disappearing across the desk never to be seen again, and once again you have to knick a screw from an old pair of glasses – lucky it fitted – well the thread was the right size so that will have to do!