Tony,
Help me here, was there also a surveyor's measuring device
which was a steel band that had brass markers clamped to it
at predetermined intervals?
Somewhere in the fog of my memory I remember seeing something
like that rolled up single file in a very narrow canvas "spool".
Cheers
Peter H in Perth
---------------------------------
From: "Tony Blanks"
To:"JAMES THOMPSON"
Cc:"oldtools List"
Sent:Fri, 18 Apr 2014 17:53:49 +1000
Subject:Re: Chains: was [OldTools] Why is 16" so important?
On 18/04/2014 3:37 PM, JAMES THOMPSON wrote (in part):
> >From Wikipedia:
>
> "A chain is a unit of length. It measures 66 feet, or 22 yards, or
100 links, or 4rods.
Jim,
Don't forget the poles and perches, each of which is the same length
as
a rod, 16'6".
The physical iron or steel gunter's chain which was once used by
surveyors contains 100 individual links, each of length7.92 inches
(that
is a fraction under 7 15/16ths of an inch for those who have mastered
neither metrics nor decimals), with a loop handle on each end to
stretch
it out straight, and brass tags at intervals along the chain, each
differently shaped to allow easy recognition.
By the time I started (and finished) as a "chain-man", a surveyor's
off-sider, gunter's chains were of mainly historical interest, albeit
I
used them on, along with a chainmans' staff and axe for the
preliminary
laying out of survey lines. Short of a malicious act a gunter's chain
is just about indestructible, an advantage in rough going. By then
the
gunter's chain was superseded in use for most purposes by thin steel
bands, marked in feet and inches on one side and links on the other,
carried on a roll, like a huge cloth tape (but still one chain in
length). I can still remember the fun we had when several of these
bands were brought in by the local surveying firm to be checked and
recertified. There was a testing rig set up along one wall of the
car-park under the Lands Department building and we would upset
people
by closing the car-park for the morning while we set heaters going to
bring the air, and the test rig, up to the certification temperature
The actual certification was done by a licensed surveyor.
As the lackey, my role in this production was to run around turning
heaters on and off, unroll and re-roll bands, fetch tea and coffee
from
across the street and to be blamed. Someone must be at fault if the
gear is too hot or cold (ditto the tea or coffee). The person who
gets
blamed may not like it, but it allows the licensed surveyor to blow
off
steam if things are not going well.
Here in Australia the early land grants by which the government
parcelled out lands to settlers were all described in "metes and
bounds". Starting from an established point, usually a corner of a
previously granted parcel of land the new plot boundary would be
described thus: "From the north corner of the parcel previously
granted
to Mr Jas Smith, In a north-westerly direction for 1 mile, 2 furlongs
and three chains to a stone cairn, thence in a south westerly
direction
to the north bank of Hobbs Creek, thence by the northern bank of the
said creek, thence by a continuation of the northwest boundary of the
parcel previously granted to the said Jas Smith to the point of
commencement." And these descriptions could run to several pages for
a
block with more than four corners.
Now with reflectors, lasers, rangefinders, dimensionally corrected
aerial photographs and differential GPS some of the magic has gone
out
of cadastral surveying But it is still possible to get an
unacceptably
large "error of close" and have to start the job again from scratch,
or
to spend several days trying to find some indication of the one-time
existence of the afore mentioned "stone cairn". And many of the long
established agricultural properties have not had their boundary
descriptions converted to modern format, so Aus surveyors still need
to
be able to think in terms of otherwise obsolete measurement systems.
Any surveyors on the Porch?
Regards,
Tony Blanks
in Hobart, Tasmania, and reaching back 40+ years.......
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