In the hydrostatic case shown in Figure, $a=6ft$ and $c=4ft.$ The specific gravities of oil, mercury, and water are $s_o=0\mathrm{.}8,s_m=13\mathrm{.}6,$ and $s_w=1\mathrm{.}0.$ Pressure variations in the air are negligible. What is the difference $b$ in inches between the mercury levels, and which leg of the manometer has the higher mercury level? Note: In this latter respect, the diagram may or may not be correct.