How to Make an Erectile Sundial

You probably rely on your penis for a lot of information: how cold is the water in the pool, how hot is the person standing next to you, how tight are those slacks, and so on. But did you know your penis can also tell you the time of day? By turning your erection into a sundial you can have a unique and very personal timepiece.

Why make an erectile sundial? Telling time without a clock is a basic survival skill, like building a fire without matches. And there will be situations where you find yourself without a watch. Suppose you’re at a nudist resort. Wearing a wristwatch would ruin your look and mess up your seamless tan. Now you won’t have to worry that you’ll miss the 1 p.m. co-ed volleyball tournament.

This project harkens back to the roots of this ancient method of time keeping. Many early civilizations used phallic obelisks to cast shadows that tracked the hours and days throughout the year. You can erect a modern tribute to our ancestors’ ingenuity with a few simple materials and your own mini-monument.

What You Need

• An erect penis (yours or a friend’s)
• A cardboard disk about 1 foot in diameter, plus additional cardboard scraps
• A protractor
• A calculator
• A marker
• A sunny day

Before you begin, there are also a couple of crucial bits of information you need. You need to know the latitude of your location (where it is relative to the equator). And you need to know where true north is, so you know which way to face when telling time. You can find your latitude by looking on a map. If you are in North America or Europe, your latitude is probably somewhere between 30 and 45 degrees. The latitude does not need to be exact; an approximation within 5 degrees will do.

A standard compass will point toward magnetic north, which can vary according to your location. You want to find true north, or polar north, which is the direction oriented toward the North Star. You can find true north by monitoring the length of a shadow during midday. You can use your penis for this part also, by putting your erection through a cardboard disk and marking its shadow. If you are worried about your penis getting sunburned, or you cannot maintain an erection long enough, you can use a stick or pencil stuck in the ground, or any perpendicular post type object, like a traffic cone or a T-ball stand. Start shortly before midday, and watch as the shadow changes size. Mark the end of the shadow and its direction every five or 10 minutes. The shadow that is the shortest will be pointing to true north.

Note that midday means the time exactly between sunrise and sunset. The actual time will depend on where you are and what time of year it is. Use a newspaper or the internet to find out when sunrise and sunset is in your area. Then convert the times to military time, add them together, and divide by two to get the time at midday. For example, if the sun rises at 6:00 a.m. and sets at 7:00 p.m. , that would be 06:00 plus 17:00 equals 23:00, and dividing by two gives you 11 hours, 30 minutes. So midday is at 11:30 a.m. If you can’t find out the exact time of sunrise and sunset, approximate times are OK as long as you observe the length and direction of the shadows carefully.

Making a Horizontal Sundial

This is the type of sundial that you are probably most familiar with. The face is horizontal and round, like a plate resting on a table, and the gnomon (the part that casts the shadow) comes up from the center at an angle. The diameter of the disk you use for the sundial face should be about 1.5 times the length of your erect penis.

To make the face for this sundial you need to do a bit of math. The lines will be placed radiating from the center on one of half of the disk. Draw one line across the diameter of the circle and a single line from the center perpendicular to it (at a 90 degree angle). This will look like an inverted T. The left side of the crossways line marks 6 p.m., the right side marks 6 a.m., and the line straight up is noon. (If you are in the southern hemisphere this will be reversed, with the numbers going clockwise from 6 a.m. to 6 p.m.)

The sun goes around 360 degrees in 24 hours, so it moves 15 degrees per hour; however, the shadow of your gnomon (penis) will travel a different distance over a time interval depending on your latitude. To adjust for this, the hour line angles (the angle ø between the noon line and the hour line) can be calculated using this formula:

ø = arctan [sin (Latitude) * tan (H)]

where H is 15 degrees times the number of hours before or after 12 noon.

When you’ve calculated all the angles for the hour lines between 6 a.m. and 6 p.m., use the protractor to mark them on the dial face.

Precisely in the center of the disk, cut a hole just big enough to fit your penis through. Cut a right triangle out of cardboard where the angle between the hypotenuse and one other side is the angle of your latitude.

Lay on the ground so that the tip of your penis is facing true north (the direction your head and feet are facing will be determined by whether your penis is erect and pointing up at an angle, or flaccid/semi-erect, and hanging down). Insert it into the hole in the face, with the hour lines under your penis and your penis head aligned with noon.

Hold the dial face as horizontal as possible. Use the cardboard triangle to check the angle of your penis and make any necessary adjustments. Your penis’s shadow should be pointing toward the correct time.

Making a Vertical Sundial

This sort of sundial has a vertical face, which means you need to be standing to use it. And in order for it to get sun and cast a shadow, you need to face due south if you’re in the north hemisphere. If you are in the southern hemisphere, you must face north. Depending on your latitude, a partial erection will probably be needed, or you can use a cardboard prop to keep your penis at the correct angle. The angle between your penis and the dial face should be 90 degrees minus your latitude.

For the face of the sundial, the angle (ø) of the hour lines is calculated by a different formula:

ø = arctan [cos (Latitude) * tan (H)]

where H is 15 degrees times the number of hours before or after noon. As with the horizontal sundial, the angles of the hour lines increase from the noon line.

The vertical sundial face is laid out the same way as the horizontal sundial, but the angles of the hour lines will be different. After drawing the hour lines using the protractor, cut a hole in the center as described above.

Insert your penis into the hole while standing, with the lines and numbers in the lower half of the face and your penis aligned with noon. Hold the disk perpendicular to the ground. In most cases, you will need to have a partial erection to get the proper angle between your penis and the dial face. Face south so your penis casts a shadow.

Enjoying Your Sundial

Since sundials require sunshine, and because this method requires at least partial nudity, a sundial made using a penis is best enjoyed during the summer months. At any time of year, we strongly advise covering the penis with a sunblock of at least SPF 30 to avoid burning sensitive skin.

Besides being functional, a penis sundial makes a great conversation piece at a garden party, picnic, or other outdoor event. While demonstrating the historical roots and principles of solar timekeeping, it puts your penis to a practical use.