You had to ask

A sila is an ancient form of measure.  You can look it up at any number of places on the Internet and be told exactly how big it is, but what does that really mean?

The picture at the right represents a water clock containing two sila of water - almost exactly two liters.  A hole is cut in the container to allow the water to flow out such that the container is entirely emptied in four hours.

Note the markings I have placed on the container.  From the bottom, they represent 20/60 of a mina, 40/60 of a mina, 1 mina, 1 & 20/60 of a minaa, 1 & 40/60 of a mina, 2 mina (which is the same as 1 sila), 2 & 20/60 of a mina, 2 & 40/60 of a mina, 3 mina, 3 & 20/60 of a mina, 3 & 40/60 of a mina, and, finally, 4 mina (not actually marked), which is the same as two sila.

So each mina is enough water to count up to one hour and each mina is 60 shekels of water.  The shekel represents the amount of water that would flow out of the clock in one minute.  I didn't include it here, but there are some interesting features of the time keeping system.

Each day of the year finds the stars four minutes higher on the horizon than they were the night before.  That is 240 seconds, the basic Sumerian unit of time, called "mu-eš."  There are 30 mu-eš in one "da-na" or watch.  The water clock here would count out the time for two watches at the temple, which means that there would be 12 watches in one day, 6 night watches and 6 watches during the day.

The period of the watch is important for another reason.  The distance we know as a league, also called a da-na, is the distance an ordinary person can walk in one watch.  That comes in quite handy for computing wages.