  In a remarkable paper from 1852, Gotthilf Heinrich Ludwig Hagen measured and
explained two fundamental aspects of granular matter: The first effect is the
saturation of pressure with depth in a static granular system confined by silo
walls -- generally known as the Janssen effect. The second part of his paper
describes the dynamics observed during the flow out of the container -- today
often called the Beverloo law -- and forms the foundation of the hourglass
theory. The following is a translation of the original German paper from 1852.
