"John Cartmell" wrote in message
...
In article ,
Dave Page wrote:
The Natural Philosopher wrote:
Lobster wrote:

When topping up old insulation (Rockwool) it's normal and more
effective to lay the second layer perpendicular to the first.

I think you mean 'orthogonal'

Perpendicular is walls... ;-)

I understood what Lobster meant, and feel that "perpendicular" was quite
appropriate. After all, laying insulation foam vertically wouldn't make
sense.

'Perpendicular' without the sense of vertical makes no sense at all. What
would it be hanging (-pend-) from?

Yes it does. It only implies vertical in some of its meanings (architecture,
physical landscape) and not in others (maths and the conjunction of two
lines or planes).

A quote from Round the World in Eighty Days:

"It was supplied with two rows of seats, perpendicular to the direction of
the train on either side of an aisle which conducted to the front and rear
platforms."

Orthogonal could just as easily be vertical or horizontal as well.

Of course one could have used "at right angles to" )


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)