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Hidden : 12/17/2008
In Iowa, United States
Difficulty:
Terrain:

Size:  (small)

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### Geocache Description:

This geocache is not at the listed coordinates but is easy to locate. It's a science lab designed to show you how wonderfully made our visual system is. You will not have to use any tools. The only thing that may require some force is sliding the cache lid forward. Solving one mystery will require some patience, so if it's really cold, have that in mind. In the warm months you may need boots.

_______ _______ _______

To determine the correct coordinates, first solve this puzzle:

Clues:

Solve just like a crossword puzzle, but instead of letters each square should contain a single digit

There are no zeros

E-Across is 4 times D-Across

The 3-digit number in A-Across is evenly divisible by 5

The single digit in box-A is equal to the digit in box-F times the digit in box-D

The single digit in box-B is equal to the digit in box-C minus the digit in box-E

D-Across is the square root of 9

No two digits in the solved puzzle are the same

Once you are finished solving the puzzle above, consider the following:

42° 33.888' N, 92° 27.999' W

Replace the 888 with the three-letter abbreviation for "Department of Consumer Affairs."

Next, replace the 999 with the three-letter abbreviation for the name of the second month in each year.

Finally, using the letters you just supplied, replace each letter with the digit that is found in the box with that letter in the puzzle above.

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This is a 6-in-1 science experiment cache. The swag compartment is small but can hold a few coins etc. The cache box is locked. To open it you will have to locate the key! That will depend upon your finding a note that tells you where to look for it. Please do not try to open or reach into the home this cache is associated with. The note is NOT in there! The force of a 10-year old could retrieve the note. Once you do locate it, please make sure to replace it correctly. Fiddle with whatever doesn't seem to work; 180 degrees comes to mind sometimes. I glued a powerful magnet to the top of the cache box; Store small parts there. If any thing gets lost, don’t fret, just let me know ASAP. I have extras.

About the cache: indeed, humans are fearfully and wonderfully made! For example, our postage stamp sized retinas and our brains process visual information billions of times faster than the most powerful supercomputer. This cache is eco-friendly. I do not believe that a 20 minute presence at the cache will harm anything. Use your discretion however.

There are many things about the eye and vision that I find particularly fascinating and like to share with my students. In this puzzle cache you will have the opportunity to experience six of them yourself.

Experiment 1 involves seeing that each eye has a blind spot or more technically, an optic disc, in the peripheral part of our vision, about 20 degrees to the left or right, depending upon the eye, from your sharpest vision. The areas are in the side away from your nose. It’s at the point where the optic nerve and the retina join; there are no photoreceptors there. So how can you see what you cannot see? Sounds like an oxymoron doesn’t it? Actually you’ll simply detect it. You cannot really see the spot as a spot.

The reason we don’t spontaneously see it (wouldn’t that be annoying?) is because our brain makes up a picture to put in that area. The brain copies the pattern immediately around it and makes spreads it across the optic disc. For example, if you are surrounded by a checkerboard, you will see an uninterrupted checkerboard all the way to the edge of your visual field.

At the cache I built in a way to find this area that you probably have never noticed before. No matter how hard you try you would never detect it if you have both eyes open. With both eyes open, one eye should see what the other one doesn’t. The cache is built for your left eye only. At the cache your left eye blind spot will be about 20 degrees to the left of your straight on vision. Laminated instructions are included inside the cache. I’ve included an electrical component to the blind spot experiment too. [Note: I doubt this ,will work anymore.]

Experiment 2 involves the saccade type movements of your eyes. When looking around, like when reading this page, your eyes never turn smoothly. Instead they jerk from one image to the next, very quickly. Those are saccades. The second experiment will require you to use the mirror itself. It’ll show you something fascinating about what your brain does to keep you from getting dizzy when the eyes jump from one place to another.

Experiment 3 will employ a penlight that should be in the box. With it you will attempt to momentarily see the shadows of the tree-like (dendritic) pattern of blood vessels situated directly on top of your photoreceptors. We literally look through those thin vessels and a very look through that cover the retina.

Experiment 4 will enable you to see that the image on your retinas is actually upside down and backwards. When you are born you see everything this way! Fortunately your brain eventually sees the image as flipped over and converts it left to right.

Experiment 5 is designed to teach you how to momentarily see blood cells coursing through the blood vessels directly on top of your retinas. If you feel the carotid arteries in the sides of your neck you can tell that they move faster when your heart makes a sound. Some of them also are seen to take one vessel or another at a junction between two of them. The directions on how to see them are in the box.

Experiment 6 is the Pulfrich Illusion. It’s seen when one eye is darkened but both eyes are used. You will look at an object moving across your field of view. The object is built into the cache; it’s a pendulum. The dark filter is in the box but the pendulum is for you to find and figure out how to let down. Follow the instructions as given.

Have fun!

I am always fascinated with tiny things, including the complexity of thin layers of materials in the body. I find this to be an interesting tidbit of that type of information that I just found on the Net. All of these layers make up the retina and are within about 1/100 of an inch!

1. pigmented epithelium,
2. photoreceptors; bacillary layer (outer and inner segments of cone and rod photoreceptors),
3. external (outer) limiting membrane,
4. outer nuclear (cell bodies of cones and rods),
5. outer plexiform (cone and rod axons, horizontal cell dendrites, bipolar dendrites),
6. inner nuclear (nuclei of horizontal cells, bipolar cells, amacrine cells, and Müller cells),
7. inner plexiform (axons of bipolar cells and amacrine cells, dendrites of ganglion cells),
8. ganglion cells (nuclei of ganglion cells and displaced amacrine cells),
9. nerve fiber layer (axons from ganglion cells traversing the retina to leave the eye at the optic disc),
10. and internal limiting membrane (separates the retina from the vitreous).

Gur xrl gb gur xrl vf jvguva ernpu!

Decryption Key

A|B|C|D|E|F|G|H|I|J|K|L|M
-------------------------
N|O|P|Q|R|S|T|U|V|W|X|Y|Z

(letter above equals below, and vice versa)

### Inventory

There are no Trackables in this cache.

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