Last week, I posted about the The Gustavademecum for the Island of Manhattan, a delightfully geeky, DIY-made, mid-20th century dining guide produced by a physical chemist for the benefit of traveling scientists and engineers.

One of the key features of the guide was an elaborate series of symbols and letters that provided a lot of information about various restaurants in a small amount of space—and which look like some kind of crazy alchemical shorthand. In the original post, I included a page from the guide, so you can look at that to see the symbols in action.

Hugh Merwin, who wrote the story on The Gustavademecum for Saveur, also scanned a page from the guide's key, which didn't appear in the original story. You can see some of it above, and visit his personal website to see the full key.

This is a page from Gustavademecum for the Island of Manhattan: A Check-List of the Best-Recommended or Most Interesting Eating-Places, Arranged in Approximate Order of Increasing Latitude and Longitude — Prepared for the convenience of mathematicians, experimental scientists, engineers, and explorers. Which is possibly the best name for a dining guide ever.

Physical chemist Robert Browning Sosman passed this pocket-sized guidebook out at conferences and updated it regularly between 1941 and 1962.

The key feature: Sosman's ... somewhat unique ... observations about the restaurants he visited. And the fact that much of that information was encoded in a sort of proprietary shorthand, cribbed from scientific symbols. The result looks something like a cross between restaurant listings and an alchemist's workbook.

In each of the guide's at least 15 editions, Sosman reviewed 300 restaurants, relaying facts like cuisine and cost, as well as esoteric observations like tableside lighting (measured in lumens) and waiters' estimated IQs. All of it was written in a mashup of mathematical figures, glyphs, Greek, and astrological symbols. A sigma meant there was samba dancing. A lowercase "m" suggested that Madison Avenue types frequented the restaurant

Sadly, the Saveur.com story that this comes from doesn't include a cheat sheet guide to deciphering Sosman's shorthand. A major disappointment. Perhaps one of you can add to the information here?

See more photos of Sosman's dining guide at Saveur

A waitress poses inside an egg-shaped dining booth at an A380 theme restaurant during a media event before its official opening in Chongqing municipality, April 25, 2012. Special Class, the name of the restaurant, is about 600 square metres in size, including the six private rooms, and can serve up to 110 customers, local media reported. The restaurant officially started business on May 1, 2012. (REUTERS)