[Bell Historians]

[Frank King]

Dear Andrew,

You say...

> ... bolting [a beam] onto the surface of the
> brickwork seems a lot less satisfactory than
> building ends in.

Not necessarily.  A beam that spans the width of
a tower and is built into the brickwork at each
end will be nice and snug and there are thousands
around so the method clearly works but...

Consider what happens when a force is applied to
the beam along its length, as happens when bells
are swinging.

This force is primarily resisted by the brickwork
at the downstream end where the wall resists the
beam being pushed against it.  At the upstream end
the pull is also resisted but to a much lesser
extent.  If the bonding works loose there is
almost no resistance at all.

If the beam is bolted to the wall at each end
using modern fixings then the resistances to the
push at one end and the pull at the other are
much more equal.  The force is shared by both
walls at once rather than one at a time.

Frank H. King
The University Bellringer
Cambridge, U.K.