Carbon composition resistors are not linear above a few hundred volts.
There are resistors specifically designed for this purpose.

You can also purchase Fluke, Heath or Eico HV probe on EBay for about $20.

If you are building a high voltage supply I would strongly urge you to take
a look at some of the supplies manufactured by Collins, Heath, Hallicraftes,
Drake etc. in the 1960's and 1970's -- there are several layers of
protection, failsafe and redundancy in all the power supplies for their
amplifier so that the operator wouldn't fry themselves.

"Airy R.Bean" wrote in message
...
I'd add a caveat that when dropping down from
the high voltage, do it with a chain of series resistors,
each physically separated from its neighbour so that you
don't get flash-over. i.e., restrict the voltage over each resistor to
less than a couple of hundred.

"Bill Turner" wrote in message
...
On Sun, 23 Jan 2005 19:39:41 -0600, "Jason Dugas"
wrote:
If I do need a voltmeter capable of measuring kV level voltages, what
brands/models should I be looking for? If not, what equipment will I
need?
You don't really need a high voltage meter per se. If you think about
it, the current through the bleeder resistors is directly proportional
to the total HV, so all you need is a low-value 'sense' resistor at the
bottom of the string, and then measure the voltage across it. The only
tricky part is compensating for the loading effect of the voltmeter
across the sense resistor, but even that is basic ohm's law.