hello M....
what your son is doing is very normal and very important for development, it's not so much a behavior as it is a sort of rudimentary science experiment, and he is only trying to make sense of the world he is a part of...a sort of questioning the universe, much like the great philosopical minds have done throughout our history. how else would we know our world was in fact round, or that we circled the sun, could fly a plane or land on the moon? test, test, test. a single visionary and lots and lots of experimenting and hello lightbulb, nice to meet you cumbustable engine, and yes even a, the pleasures all mine curling iron. think theory of relitivity, the milk from his bottle is always going down, he wants to be sure that just this once it doesn't go up, and he wants to be sure again and again. you should foster his experimenting, ok milk is not exactly what we want our precious young ones dripping everywhere, a special hand picked by him (just show him the cheapies) bottle with water in it and a low flow (0-6mos) nipple on it couldn't really hurt, and since you'll be encouraging him and allowing him this freedom, you can place some restrictions on it, for example: not on mommies beautiful wooden coffee table, or her damask curtains, but right here, set up an appropriate place for him to "drip", you could even give him a plastic bowl to drip into. he will be much more apt to follow your directions and stop when you issue a no or not here, if you give him the opportunity to carry out his wishes. `children around this age need to play with water it is essential to there developement. chances are he'll curtail this dripping experiment once he is fully allowed to carry it out, ie. a week or two, and move onto bigger wetter messier experiments, but given the proper space to fulfill these playful experiments will ignite his curiosity for the world around him, don't be afraid to introduce some experiments of your own, making sure he understands proper time and place (as best as a 1 year old can) and he'll adore you for it. just be happy it's moving into summer, and great weather, you can move these experiments to the front stoop, back porch, patio, or lawn, no clean up hours of entertainment, and best of all fun with your child. and he won't drip where you'd rather he didn't at leasst not all the time and you will no longer be the other experiment he is currently undertaking... where will mommy let me drip, how long till she tells me no, what will her reaction be if i drip here? etc. you get my point, keep him from directing this unwanted experimental play, and instead take charge by directing a grander more elaborate experimental play that keeps the both of you happy.