FLUIDS DEFYING GRAVITY. 



secure such exact equality in the length of the 

 legs, the filling of the lower orifices, the wet- 

 ness of the ends adjacent to these orifices, 

 and the stillness of the air in their neighbour- 

 hood, as to balance a poker on its point. We 

 could not avoid some slight inequality which 

 would destroy the balance in so mobile a 

 substance. 



Let us, then, go on to the case where the 

 orifice of one leg is distinctly lower than that 

 of the other, as at E and F. In this case the 

 atmospheric pressure upwards in the two legs 

 is once more balanced, and so is the weight of 

 water-pressure between the levels H and F, in 

 which the two water columns are of the same 

 height. The water between these levels in 

 the two columns therefore neutralises, by its 

 downward pressure, equal portions of the up- 

 ward pressure of the atmosphere in the two 

 columns, and leaves the balance undisturbed. 

 But the water between the levels E and F in 

 the left leg is unbalanced, and neutralises an 

 additional part of the atmospheric pressure 

 upwards in the left leg. The resulting pressure 

 upwards in the right leg being greater than 

 that in the left, the water is driven upwards in 

 the former and runs down and out of the 

 latter, with a force which depends upon the 

 height of the unbalanced column of water F E 

 at first, but more afterwards as the column of 

 water in the right leg shortens upwards. 



