This is the thread where we use our collective wit to solve questions that have somehow bothered you, using our expertise to make the world a more comprehensible place. My question concerns vacuum cleaners (not standy up ones, but ones with the suction tube). The suction tube in question always in my experience has a little sliding cover to a hole. What is the function of that hole? I've never found it to be of any practical use in the slightest.
