I don't think gaffer's tape is recommended for glazing use,
but I think it'll hold for a little while, keep the draft through
that window down to sane levels, and prevent the top pane from
coming completely loose and plummetting to the sidewalk.
This isn't the first window here to suffer this failure mode.
The wood of the frames is old and deteriorating, and the joints
at the lower corners of the upper sashes of some of the windows
on the front of the house are coming loose. I've got a couple
held together by sticks the right length wedged between the
bottom edge of the upper sash and the sill below.
I'm not the handyman that the previous owner is, so when I
fix these for real it'll probably have to be either screwing
metal brackets (uh, I mean 'flat corner irons', I
think) onto the fronts of the sash-frames or saving
up to get the windows replaced. Replacing the windows with
modern, better-insulating, possibly heat-reflecting windows
that look enough like the old ones to meet the local historical
preservation regulations (which only apply to the fronts of
houses here) would be the best long-term answer, given how much
it could save on heating and cooling, but like so many potential
long-term savings, coming up with the initial capital is the
obstacle.
I think of it as being like the activation energy of an
exothermic reaction. If you can light the thermite you'll
get a lot of heat out of it, but if you don't already have
an ignition source hot enough to start the thermite going,
all you have is a pile of mixed metal-dust.
If I understand the current economics of photovoltaic
solar correctly, I could save money over the long haul by
putting enough solar panels on my roof, too. But that'd
cost even more up front than getting the windows replaced.
(Eighteen windows total, eight subject to historical
preservation rules. All of them currently drafty, some
through gaps between the sashes or between a sash and its
track, some through gaps around the panes, some through
gaps around the frames where the opening in the
wall has deformed slightly over the last hundred and forty
one years.)
Aaaand there goes a really ominous tearing/creaking noise
that I do hope wasn't some part of my house (like more of
my roof) getting town off. Hey, the Internet connection
is still up (if a bit laggy); that's a good sign. It means
the antenna hasn't blown away. I'm hearing objects of various
sizes and compositions rattling and clattering up the
street, as well. Some of the wooden-sounding ones are
fairly bouncy. I should go take another look and match
sounds to objects.