I bought a number of daylight-loading tanks to photograph for this website or to obtain instruction manuals. Among the many were two Essex 35s. One was exactly as the instruction manual described; the other was not. The latter had been modified but why and by whom I have no idea. When I opened the package, I was surprised to find in a bag with the film-cutting template, the dome-shaped piece of shiny metal that sits in one end of the cassette holder, two metal pins and a rubber grommet. The dome in the tank had been replaced by an annular-shaped piece of metal that projected through the hole in the back of the cassette holder in which the foot of the dome normally sits. I then realised that the lid of the tank had, in its back wall, a hole in line with the hole in which the dome normally sits. When one of the two pins was pushed into this hole, the tank lid was locked in place – not a usual feature of this tank.
I found no problems in developing a film using a standard cassette because the annular piece sitting in place of the dome, at 9.55 mm diameter, fitted perfectly the recess in a standard cassette of 9.4-9.5 mm. Locking the lid in place with one of the pins also ensured the lid could not fall off when the tank was being emptied.
These first three photographs show the normal, unmodified tank.
The dome, according to the manual, can be reversed so that the back wall of the cassette holder is flat. This is done to enable Agfa Karat cassettes to be used.
The next photographs show the modified fitment and how the lid is locked into place by one or other of the two pins I found in the bag.
Neither of the pins (only one of which can be used at a time) reaches the cassette so cannot have any role in controlling movement of the film. I have no idea what the rubber grommet was used for or even whether or not it should have been in the bag. The only possible clue is that its smaller end will fit into the ring at the front of the cassette holder leaving a flat rubber surface facing inwards.
So, I have a modified tank that could be returned to normal but which works perfectly with standard cassettes. The first questions are: why the tank was modified in this way? Was it for a type of cassette that would not fit without the modification? Was it to provide a locking mechanism for the lid while providing a possibly improved method of holding the bottom of the cassette in place?
Then it is a matter of who did the modification. Could it have been a factory modification? Or was it done by a skilled engineering worker, a user of the tank perhaps? If the latter, there was certainly skill involved because the hole in the lid was drilled precisely in line with the hole in the back of the cassette holder. That centre cannot have been an easy point to determine. The new fitment is also beautifully made. There are two points which suggest to me that it was a post-works modification. The first is that the two pins are the sort that one might find in any engineering workshop. The second is that the hole drilled in the lid has a very small chip in the bakelite on the exterior.
With the tank came the instruction manual and a cardboard calculator for Johnsons of Hendon Unitol developer. Both the tank and the calculator were bought from Bell & Webster, Qualified Dispensing Chemists (i.e. a pharmacy that sold photographic gear, as so many did in the 1950s) of 110 Lichfield Street, Walsall. Walsall, to those unfamiliar with the geography of England, is in the heart of the industrial West Midlands – just the sort of place where the expertise to modify a tank could be found.
Can anybody help solve the mystery: why and whodunnit?