David,
You can also measure the rainfall amount by weight.
1cc of water weighs 1 g (strictly at 4C, but close enough at normal surface
temps).
For a 5 inch gauge, devide the weight of collected water measured in grmmes
by 12.6677, to get the rainfall equivalent in mm.
Don't forget to measure the container empty first, or when dry, and of
course, make sure your scales are accurate to the nearest gramme.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.woksat.info/wwp.html
or
www.btinternet.com/~wokingham.weather/wwp.html
"David Mitchell" wrote in message
...
What a time to break my measuring jar, on the way to the gauge at
midnight.
I could only measure the rainfall in cc's - does anyone have a conversion
to
mm's?
My Davis is under-recording currently (haven't yet fixed it) hence the
manual gauge and the Davis recorded 51.6mm!
The manual gauge inner holder had overflowed slightly, only the second
time
I've known this, previous occassion in Penistone with about 115mm - will
check that.

--
David Mitchell, 70m amsl, Langtoft, East Riding of Yorkshire.