To see roughly where to put the hairspring on a balance so that the watch is in beat, after putting in a new hairspring, look at the opening in the cylinder; this should face the 'scape wheel. Usually there is a small dot on the balance rim against which the hairspring stud should be placed. To try finally, see that, when the watch is wound up, the balance when stopped by the finger has no more tendency to stop on one side than the other, and always starts off immediately it is released.