I haven't seen this point made in other postings, so I'm adding my two
cents, recording hygrothermographs are useful because they give you an
instant reading of an area.  Or if an area develops a problem you'll know
immediately, not 2 months later when you download the datalogger.
Downloading the datalogger doesn't take a great deal of time for one
unit, but it does take some time.  Bill Lull was at OHS on an IMS-CPS
grant for an environmental survey and he recommended to us the use of
both.  I have 6 hygrothermographs, 7 dataloggers, and an aspirating
psychrometer.  I use the dataloggers for monitoring of spaces,
downloading about every 2 months; and the hygrothermographs for "spot"
checks and if a problem occurs that I want instant data on.  I have to
admit that I don't recalibrate as often as I should, but I also don't
move the hygrothermographs around very much.  The other problem with
hygrothermographs is going around and winding and changing charts every
week, something that I wasn't always successful with.

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Marsha Matthews

Director/Museum Collections         Oregon Historical Society

1200 SW Park Ave.                            Portland OR  97205

Internet: [log in to unmask]           Telephone: 503/306-5274

FAX: 503/221-2035



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