it is used to make small focus adjustment, especially when using the high power objective , and permits gradual changes in thw elavation of the tube for final accurate focusing​

They break down fat

Answer in 2009 barack obama signed into law the family smoking prevention and tobacco control act, the new law (h.r.   1256) represents the most sweeping action taken to date to reduce what remains the leading preventable cause of death in the united states;