In article >, default says...
>I quit using a hydrometer years ago. It doesn't really tell you
>anything helpful, you risk contamination of the wort . . . what is the
>use?

Off the top of my head, I can think of several good reasons other than
calculating alcohol:

For beer, you need one to determine

1) mash and brewhouse efficiency
2) adjustment of hops in the kettle
3) problematic fermentation
4) when to start lagering phase
5) when fermentation is complete
6) wort fermentability


And since you crossposted to a winemaking group:

1) adjustments/dilutions prior to fermentation
2) problematic fermentations
3) final adjustments

I'm sure I left out a bunch.

The risk of contamination from taking a small sample post fermentation is nearly
zero assuming you can use reasonable sanitation procedures. For wort, the
greatest risk is prior to fermentation. If you're not able to take a small
hydrometer sample of fermented wort without introducing an infection, there's
little hope that you'll be able to produce a decent non-infected beer to begin
with.