Returning to the letters that had the same area. It
seemed reasonable to suppose that the rectangular
quality of say the 'B' as opposed to the more overall
square shape of the 'H' should be allowed to reflect
in its space, in spite of their area equality. A further
trial with some other letters led me to the same
conclusion. Though this conclusion is only partly
true, it did lead me farther along the trail. With the
help of an engineer we made upa small gadget which
made rectangles of the exact size in which a letter
would fit. We counted all the millimetre squares in
the letter and then reduced the rectangle in exact

8

proportions until the same number of squares could
be counted within the rectangle. This was hard labour
but we found the result satisfactory.

Our first instrument for spacing

Soon we were measuring our letters by transmitted
light and a photo-electric cell, and then reducing the
characteristic rectangle to give the same light value.
These rectangles came to be known as letter blocks,
and by adding a constant to their lateral width we
were able to achieve reasonable spacing. But of
course we still had to position the letters by eye
within theirspaces.

Having by now learned a little about light sources
and photo-electric-cells-it occurred to us that the
centres might be found if some kind of light wedge
was put over the letter so as to exclude light from its
vertical centre but permit light with increasing
intensity to pass through either side. And by moving
the letter to and fro from left to right under this wedge,
it could become positioned where at least the light
was balanced. This seemed to have promise, and
although we still did not get the eye-preferred
centres we were looking for, we did get centres that
tended away from area and towards the required
optical centres (Fig. 6).

Suddenly, it dawned on methatthefinding of

Fig. 6

centres and the spaces were one and the same thing.
Find the right centres and you will then have in light
value terms, through the wedge, the correct space. In
theory we were getting somewhere. I n fact none of us
had the technique of making wedges. Kodak would
make us wedges if we told them what sort of wedge
we wanted ! It would be expensive anyway !

Then started the long nightmare of wedge-making.
First painting them on pieces of film actually over the
letter to see how it moved the centre. At one time we
made tanks out of three sheets of glass glued with
Araldite and filled them with inky water measuring
the amount of ink to water. The photographer was

not amused when the tank burst in an upstairs room
above his shop ! Next we constructed about 100 thin
strips of card carefully graded by painting from white
to black. We then photographed them to make a
wedge. But alas, nothing quite worked. Should the
wedge be circular ? It seemed a good idea, and
surely the eye more truly matches this approach, but
the results were worse. For this purpose we cast
wedges in brass matrices with gelatine and dye. The
first signs of hysteria were setting in !

A more scientific approach

A new approach to wedge-making must be found,
we said. Fortunately Dr Colin Quinn came to our aid.
He gave us precise calculations for different
progressions so that we were able to make large
wedges on Bristol board with a ruling pen. By this
means we made very accurate first, second and third
moment progression wedges and our third moment
wedge began to show the way.

By the nature of its construction the wedge was very
dark. Undaunted, Dr Quinn recalculated the wedge
so that we could construct it out of circles, thus
enabling us to get more accurate readings towards
its centre. The illustration is of a second moment
wedge made in this way (Fig. 7).

You may wonder why a bunch of amateurs without