So what’s a Cardan grille?
Girolamo Cardano (1501-1576); Italian doctor, mathematician and degenerate gambler. He was like the Dr. Stu of the 16th century. Today, we know him as the author of some of the very first textbooks on algebra. But he is also credited with inventing a form a cryptography known as the Cardan grille or Cardan screen. The grille is usually a sheet of metal or rigid cardboard with holes cut in it. If you have both the encrypted text and the grille, you simply lay the grille on top of the encrypted text and read the plaintext through the holes. The Cardan grille was a popular way to transmit coded diplomatic correspondence in the 17th and 18th centuries; it was kind of the emoji if its day! If the encrypted text is written cleverly enough, i.e., as a letter or grocery list, it can be nearly impossible to crack the encryption without having the corresponding grille.
Below is an example of a Cardan grille. I recommend using MS Paint to read the grille instead of trying to cut the holes in paper. Now, of course, this means you probably won’t be able to do this on a phone or on a Mac; you will need to use a PC. Either save the image and then open it with MS Paint or take a screen shot and paste it into Paint. Then select the grille and make sure the “transparent selection” option is checked so that you can see though the holes. Now, by placing the grille over the matrix of letters you can read a hidden message. The message is read from the top left corner to the bottom right corner. The massage has nothing to do with finding the cache, however; it is just to show you how the grille works and to acquaint you with using MS Paint.
To find the actual cache coordinates hidden below, you will need to make the grille by punching the holes yourself. The coordinates are hidden in the large matrix of numbers. Below the numbers is a grille with 30 books of the Bible below black boxes. You can “punch” holes in the grille by opening both images in MS Paint, or taking a screen shot and pasting it into Paint. Select the color white. Then select the Color Fill tool or the Paint Bucket tool depending on which version of Paint you have. Click on the area inside the box you want to “punch out”; this will turn the box white and allow you to see through it. You must only punch out A FEW of the boxes to make a grille corresponding to the cache coordinates. Once you think you have the correct boxes punched out, paste the grille on top of the numbers making sure the transparent selection option is on. To know which boxes to punch out, you will need to find the second message hidden in the letter matrix above. Not the message you read using the small grille above, but another one.
Congratulations go to jimandjoanne for FTF!
You can check your answers for this puzzle on GeoChecker.com.