The old page that described the hydrostatic equations has been removed and all links to it on the PDAS web site have been changed. You may have arrived here because you bookmarked the page or by way of a link on another web site.
I no longer write pages that contain mathematical expressions in the form of bitmaps. From now on, I will use MathML to build such pages. For the benefit of those who do not have browsers with math capability, I also have the page as a Portable Document Format (PDF) file.
You may read the page describing the hydrostatic equations. XHTML+MathML, 12KB or PDF, 69KB.