The usual method is by means of a "tipping bucket" device. It is essentially
two chambers either side of a pivot which are a lot easier(for me) to sketch
than describe. A gathering funnel is placed over the pivot point and as one
chamber fills, it upsets the center of gravity and tips. This places the
other chamber under the funnel and empties the first chamber. This repeats
back and forth and the "tips" are counted electronically. Quantitation is
derived from the volume of the chambers and the area of the gathering funnel.
The larger the gathering area and smaller the chamber volume, the more
sensitive the device in terms of tips per unit time.

A search on "rain gauge" AND "tipping bucket" should yield both commercial
versions and, perhaps, a home-brew unit. Email me directly and I'll scan my
sketch if you don't have any luck.

Steve Kerrin (a new lurker and learner)
Escondido, CA



Wesley Moore wrote:

> I have a friend interested in making his own logging weather station. I
> was wondering if anyone had any ideas on how to measure rainfall for such
> a project.
>
> ___________________________________________
> Wesley Moore
> RMIT - BEng/BApp.Sc. 2nd Year
>
> wmoore@cs.rmit.edu.au
> http://wmoore.tsx.org/