"tdacon" wrote in
:



"David Howard" wrote in message
...

Garrett Wollman wrote, on Mon, 06 Oct 2014 04:50:01 +0000:

In woodworking, a spline is a long (and perforce rigid) bar of
material used to join two grooved work pieces (essentially acting as
a two-sided "tongue"), running cross-grain and providing greater
strength than a simple butt joint by greatly increasing glue surface
area. I suspect the same sense exists in metalworking as well.

In the boat-building craft, a spline is a long thin strip of wood with
very uniform bending characteristics. It's used in a process called
lofting.

The original definition of spline (according to the OED) was
simply a long thin strip of wood - used to keep two boards
aligned and flat (the cross-grain application Garrett
describes is more modern - and depends on modern glues,
I think).

A later definition is a spline was a rigid bar used to lock
two pieces together - typically a wheel on an axle or something
similar. Today we'd usually call that a key.

Because spline stock tended to be long and relatively thin, the
name transferred to the lath used in lofting for shipbuilding,
as David says. By extension the same name came to be used for
small lead strips which would hold a curved shape - today we
call these flexible curves (and they're usually plastic-covered).

Curves laid out with a spline (i.e. a flexible curve) were
logically called "spline curves", and in the early days of
computers mathematicians trying to analyse such curves by computers
came up with math functions to represent the curve as a series of
short segments; those functions in turn came to be called splines.
By a further extension, the particular curve created by a spline
function is also called a spline.

Probably more than anyone cares to know :-)

John