  We provide an alternative approach to a problem posed in the article
"Hourglass of Constant Weight" by Volker Becker and Thorsten P\"{o}schel, which
appeared in Granular Matter 10 (2008), 231-232, i.e. 14 years ago. Our goal to
return to this article after so much time is purely pedagogical. Although there
is a slight and subtle inaccuracy in the derivation of equation (8) in the work
of Becker and P\"{o}schel, which we correct, we use this circumstance only to
give a detailed pedagogical exposition of an excellent physical problem and to
show the pedagogical usefulness of the concept of momentum flux when
considering the mechanics of systems with variable mass.
