Show minute measurements because tho the balanco wheels wheals of 0 watches expand and contract wit changes cli angea of temperature they ru roii n slower and faster ne occo cording nUng to circumstances cum cunis stances lances by malcina them of dlf dif ferent kinds of metal having different deg ieca of expansion with increase In creaso of temperature tho tha effect of their changes on the lie running of watches way may bo be almost entirely eliminated dut in dealing with such a pro blent it is necessary to know tile expansibility of the metal employed A means meana of measuring it Is furnished by an instrument called it a lu in which a system of delicate lovers levels or a chain of gear wheels tile the motion of a pointer over a graduated scale hundreds of time at it a meeting of the physical society in london not long ago a was exhibited which had a tion lion of 1500 times so that tile the chatine in alib hb length of a piece alce of steel caused by a chiglo degree of rise or fall of temperature was waa clearly measured by it |