UKTC Archive

Hi Scott

Liz

From: "Scott Cullen" <dscottcul@xxxx.net>
Reply-To: uktc@xxxxxxxxx.co.uk
To: UK Tree Care <uktc@xxxxxxxxx.co.uk>
Subject: Re: PICUS
Date: Wed, 12 Feb 2003 07:14:31 -0500

Liz it pretty clear, but can you confirm, you need the chord distance
(distance across) not the arc (distance along the circumference)?  This
would be the distance traveled by the sound wave.

While larger trees might be less commonly encountered they are the ones

with

the potentially greatest value and attached public sentiment. These are

the

ones where we need the nest information and where we might be most

concerned

about the negative impacts of drilling.  (If we have a common roadside tree
24" in dia. which is 0.01% of our population and we reduce its life by 10
years by drilling in order to determine it's OK to leave in place, who
cares?  The public interest is best served.  If, by contrast we have a one

of a kind historic specimen 5' across is it acceptable to take 100 years

off

its life by drilling if we can get an acceptable picture with PICUS?)

So I think the practitioner would really want to know the proper procedures
for calibrating the instrument for big trees.  I imagine you could
approximate dia from different aspects to do a scale drawing or with a
transit instrument do it quite precisely.  The PICUS web site does not give
any detail on this.  I haven't had time to dig out any of Stefan Rust's
papers to see if it addressed there.

Scott Cullen

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