[ "Avoir une araignée au plafond" / " To have a spider on
the ceiling"
is the French equivalent to "having a bat in the belfry"]
This is the place where I can freely be : " a bit touched
you know".
You can not be troubled by what I write but only by your own
judgement about it.
Point of importance to me is not having what I write approved (or
rejected).
Point is rather to make you stop for a moment, having shed all
pre-conceptions and having put
aside
past
'read
or heard' that you readily accepted without real examination.
Just exercise
your own
thinking power in a critical
( intellectually that is, not affectively ) way.
To do that you will have to suspend all disbelief till having
finished reading a whole topic and then
read it again having this time
engaged you open and honest critical thinking.
Main point is having you, Reader, to go and shape your own personal
view.
So again, please!, do not fall back on 'automated,
pre-digested, un-examined' response you have read
or
heard elsewhere.
A much useful stance will be to be 'virginal' and think on
your own as if
you had never met the topic.
You are not sure there is a
difference
that makes a difference ?
If by any chance it was not quite evident before it should be by now.
Knots are made using cordage ( we will by commodity put aside other
materials ) that are
following a "self avoiding walk".
Please take note that it is knots / bends / hitches and not splices
that are the point
in
case
here.
Avoiding as in not 'truly intimately meeting' itself , not 'mixing'
with itself.
Think about it like that :
- when a highway is 'crossing' another one there
is
no risk of a collision,
- when two streets intersect each other you better be careful,
- electric wires are crossing and not intersecting with other wires or
water ducts.
Another example :
if one day not made like the other days, in Paris, le Métro
were to go
intersecting La Seine
(fleuve) or if in London the Underground
were to go intersecting The Thames (river)
better
have a scuba gear in good working order handy.
Fortunately, till now, both underground
railways are crossing (either
under or over) their
respective body of water.
Note :
in a real knot there are crossings but in its planar projection,
its diagram on a sheet of paper
(more so on your PC/Mac screen ) these
crossings are represented by intersections. ( ink
can be admitted to be
everywhere on the same level and not going under or over, though
one
could conceive
of the graphite layers left by the paper pencil as being on different
levels )
NOW SPLICES (in laid or in braided cordages) ARE
DIFFERENT
No
self-avoiding walk here for the cordage as a 'whole'
even if strands
or fibres
are still avoiding each other and themselves.
In modern braided cordages splices are rather
a 'confluence' where the
cordage goes into
itself playing Orobouros.
( confluence : like a river meeting another river.)
By the way in English you seem to have only 'river', in French we have
'rivières' / river, that
is a body of running water meeting
another one and we have
'fleuve',
for which you do not
have the equivalent or I do not know it : it is
for a river
that is ending in the sea
.
In spliced laid cordages the 'intersection' can be thought of as
forming
what
topologists
call
a 'double-point'
even if a splice
diagram can be drawn without a double point !
( double
point of crossing as there
is a top and a bottom
crossing , a sort of piling up of
crossings)
Double-point appear when you try to get "the unknotting number" that is
modifying the
nature of crossings.
To go from a H to a L or from a L to
a H crossing you have to go through a "double-point".
Making
'trambles' you can use them too.
Nevertheless pseudo or real double point can be made into a tool :
A 'double point' is 'totipotent', it can resolve either in a
"H" ( High)
or in a "L" (Low)
crossing.
Hence the 'cordage intertwining' in my illustration can give
rise to different knots depending
on the choice between "H" and "L".
Illuminate it brightly and just look at the projected shadow taking
care that each intersection
is not superposed on any of the other ones.
Question : which knots
will produce identical shadow images.
We will come back to that again when looking into
'shadow'.
SOMETHING NOT TO
FORGET ABOUT HITCHES : D/d
D/d is the ratio between the larger diameter and the
smaller one.
D/d ratio is quite important to keep in mind when imposing a
curve to a cordage.
In particular while using a pulley it must never be forgotten
: continued integrity of fibres
depends on a correct ratio being observed.
As for a hitch
not only D/d play a
role on the fibres of the cordage but has a direct influence,
that
cannot
be neglected, on the surface and friction.
By the way : fibres can be damaged by
'compression'
and not only by 'elongation'.
(more to come later in "ropes
and cordages" pages )
