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gunter's chain was superseded in use for most purposes by thin steel 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.......