A Map that's More than Its Information

I just saw this cool historical map of Saint Paul on BlueSky, thanks to a user named s0phistry:

He described it as "Municipal boundary changes in St. Paul MN. It capped out in 1887, just 40 years after its founding."

It's very worth clicking on it to look at the detail. I don't know what year it was made, but in addition to showing how Saint Paul grew, which is interesting enough for a local, it's also a showcase of pre-computer cartography. There are little dots and various patterns to indicate the decades parts of the city was annexed, alternating black/white lines to indicate boundaries between annexed areas, and "Scotch rules" around the circular number labels.

This map was made with ruling pens (or maybe Rapidograph pens if it was from the 1970s/80s) and lettering templates. I know, because I was taught to make maps just like this in college in about 1980.

We got to use Rapidographs, but first we had to use ruling pens to understand the method that had been dominant forever. 

You could set the line width of a ruling pen by turning that little gear in the center, but it wasn't an exact thing. Then you would use the dropper from a bottle of ink to fill the space between the two metal parts. Thin lines were easy to control because the ink stayed in well, but with wider lines there was less control of the liquid between the pieces of metal.

Rapidograph pens were a more advanced mechanical pens that came in sets with finely machined metal barrels at defined widths. You filled the plastic reservoir with ink, put the parts together, and when the narrow plunger touched paper inside the barrel, the ink would flow at the width. 

The problem with these pens was they dried out very easily. They needed to be stored at particular humidity if there was ink still in the reservoir, or you had to clean them out completely and waste a lot of ink. They were also expensive compared to ruling pens. But I loved them nonetheless.

I had a set like this:

And then there's the Leroy Lettering Set you needed for all of the words. I really wanted one of those of my own, but I never got one, and computers soon made them obsolete. 

There were alphabets and numbers of different sizes in the kit. As the photo shows, you would put the pin in the engraved letter you wanted, and your pen above the paper in the correct spot where the letter was supposed to go. It was not too hard with a Rapidograph, but much harder with a ruling pen, I remember. One mistake and your whole map could be ruined with a huge ink blot.

We used X-Acto knives to scrape off ink from the top layer of the vellum we worked on, and a product called Pounce that helped somehow. But it was better to not make a mistake in the first place. 

Imagine the spatial judgment it took to make a map like this with these tools, in ink. There may be some scrape-away corrections on the original that aren't visible here, or maybe not. Hats off to you, map-maker of the past.