So, You're Lost in Time: Determine When You Are
The first responsibility of any sensible chrononaut is to know when they are! You are, of course, free to be eaten by any timeline’s combination of wolves, saber-toothed cats, and hyperintelligent lizards, but please be sure to throw your chronometer and guidebook free of the blood for ease of retrieval. We thank you.

In that case, chrononaut beta, throughout the history of Earth, the landscape has undergone fantastic changes. So the intrepid explorer must look away from familiar natural landscapes to place themselves in time–specifically up to the stars.

The night sky can be thought of as two hemispheres combined to form a sphere around the Earth. Star are embedded in the “celestial sphere” like careless adventurer reentering a timestream within the ceiling. A circumpolar constellation will always remain above the horizon because of its proximity to the center of the planet’s rotation axis, making them an ideal reference point to observe the gradual wandering of stars. Since this movement is incredibly small each year, the degrees of movement are represented with equally small units: the arcsecond*.

Consider the plight of Edmund Halley (1718 A.D) when he noticed that the three bright stars Sirius, Aldebaran, and Arcturus were almost half a degree (~1800 arcseconds) different than Hipparchus (190 B.C) described! The only way to make sense of this was for him to realize that stars must be in motion, and over thousands of years, they had moved far enough to be apparent to the naked eye. So don’t hold your breath waiting–without a proper oxygen unit attached.

The stars’ movement (here, proper motion [μ]) is the sum of its own motion and relative position to Earth. This proper motion is only apparent over hundreds of thousands of years. Also, as stars are nocturnal, this strategy will require waiting until night; but patience is the virtue of non-digested explorers.

One familiar circumpolar constellation is the Big Dipper within Ursa Major. Most of the stars within the Big Dipper are believed to have formed at the same time and move together as a group–except, that is, for the stars Dubhe and Alkaid. These stars are further away from the main cluster, and are moving in a different direction, which will act to emphasize how the shape of the Big Dipper will change predictably over time. To estimate your epoch, compare the degrees of shearing to your expected time period.

With no instruments, the degree a star moves can be estimated within a few degrees of errors by hand. For reference, the angular distance between Mergrez and Dubhe during the years around the first moon landing in the 20th century is ~10.3°.

Southern Hemisphere:
If the night sky does not include the Big Dipper, it is more likely that you have found yourself in the southern hemisphere of Earth than another planet (probably). Fear not! The same principles apply for the circumpolar constellation Crux in the southern hemisphere (where the angular distance between Mimosa and Delta Crucis is ~4.3°). Otherwise, you are free to panic for the standard allocated time of three minutes.

*Remember, of course, that an arcsecond is a unit of length–not time. One arcsecond is a fantastically small (1/3600th of a degree) slice of a circle, and it is used to describe the arc of a star moving across the celestial sphere
1 degree = 3600*arcseconds and 1 arcsecond = degrees/ 3600
Consider a star with a proper motion of 0.1 arcseconds per year: After 100 years the star moved 0.1*100 = 10 arcseconds


So, You're Riding the Rails: Hobo Signs and Symbols

The roads can be a dangerous place. Depending on when and where you’ve found yourself, this can vary from dogs to hunting packs of dinosaurs (either the traditional reptilian or reconstructed robotic ones), to, of course, disease. In search of work—or at least better weather—hundreds of thousands of transient people took to the road in the USA and Europe through the war-ravaged 19th and 20th century. 

While most contemporary sources use the outmoded terms interchangeably, there is an important distinction between a hobo (someone who is currently homeless and looking for work) and a tramp (who is homeless and not looking for work), although both traveled either on foot or by taking advantages of railyards. Thanks to the popularization of trains during this time, any dutifully-cautious chrononaut can traverse across thousands of miles of open country with relative ease. However, no time has ever been kind to the poor, working or otherwise. To move safely from town to town can be difficult when being homeless was enough of a crime to land in prison. As a result, symbols began to crop up, left by ingenious hobos, tramps, and (sometimes) thieves as warnings and aids for fellow travelers (and any keen-eyed chrononauts). These markings, carved or chalked into walls and gate posts, deftly judging the character of the homeowners or town. Because of the symbolic nature of markings, variation in meaning exists within communities, but listed here are the most common translations of these cryptic hobo hieroglyphics.


*Please note that while the general symbol is consistent, the execution can vary depending on who left the symbol, (e.g. any image resembling a ‘cat’ will represent a friendly women)


Folklore Survival Guide: How to Kill (or Cure) a Wendigo

Origin and Description

The Wendigo (also known as Windigo, Witiko, Wiihtiko, Kokotshe’, Atshen, Atcen, along with many others) is a cannibalistic ice spirit that haunts the folklore of the Chippewa, Cree, and Northern Algonkian people of North America. Depending on the story, there are different ways to create a Wendigo. Most commonly, it is an insatiable monster created when the spirit of a Wendigo possesses a person suffering from grief, isolation, or abuse and they are traditionally transformed into a monster when they revert to cannibalism during the harsh North American winters. In addition, a person can be cursed to transform into a Wendigo by shamans. Few people are protected from Wendigos, with stories of men, women, children, and even animals being possessed.

A Wendigo is cursed with incredible strength, violent aggression, and, most importantly, a cold heart of ice. Emaciated by an endless hunger, the Wendigo will eat almost anything including rotting wood, swamp moss, mushrooms, and, most troubling of all, human flesh.

Physically, a Wendigo is unmistakable. It wears no clothing over darkened skin toughened by rolling in resin and sand. With each meal, it will swell in size, with elongated legs, feet and large eyes to aid in hunting. It has no lips and mouth filled with enormous crooked teeth. Wendigos are incredibly hostile creatures and although they rarely encounter one another, if two Wendigos meet they will fight until one is defeated and devoured by the victor. 

Symptoms and Signs of Transformation

Early symptoms of transformation into a Wendigo can be gradual, but without help will inevitably intensify over time. This includes rigid muscles, nausea, vomiting, neurotic fury, and an aversion to ordinary food. At this early stage, through the support of friends and family, an affiliated person can sometimes make a full recovery, but historically, those who think they are becoming a Wendigo have been asked to be killed. With no intervention, as time passes, a cursed person will develop an unnatural craving for human flesh. Once they satiate their desire for human flesh, the Wendigo will only grow hungrier and larger, swelling in size, and their heart will turn to ice. Some of the earliest symptoms can be relieved by thawing an afflicted person by a fire. While this is not a cure, the heat can alleviate the strongest of the cannibalistic tendencies for a time.

How to Cure

Wendigos are dangerous monsters which can make it difficult to safely interact with them to administer a cure. Traditionally, a Wendigo can be cured by forcing them to ingest melted fatty meats like duck meat or, particularly, bear fat. This treatment is not meant to be taken nutritionally, but emetically, in order to induce vomiting to disgorge the intrusive icy heart of the Wendigo. The concoction is meant to melt the icy heart, which can be vomited up. The meal will cause the afflicted to vomit a large quantity of melted ice and after some time, they may return to normal. 

How to Kill

If a Wendigo cannot be safely cured, the victim must be killed and the remains burned. The body must be completely burned to prevent the Wendigo from returning to life. When burning the Wendigo, the body will be destroyed by fire, but to be completely killed, all stories focus on the belief that the Wendigo’s heart of ice must be destroyed as well, which can be difficult since it will not immediately burn. As a result, the ice heart can be taken from where it remains in the fire and pounded or chiseled into smaller pieces to make it easier to be melted in the fire. Finally, the blood and any clothing it might still wear must be burned to ash and the area left alone until the land regrows.


So, Angles: Making a Protractor, as Simply as Possible


The mighty protractor: an endlessly versatile tool that forms the backbone of any chrononaut’s (government-issued) toolkit. A protractor measures angles–the distance between two diverging lines–making it particularly useful in navigation and astronomy.

The protractor’s design has changed very little from its earliest recorded illustrated form in Thomas Blundeville’s 1589 map-making guide: Briefe Description of Universal Mappes & Cardes. Blundeville illustrated a half circle, but a protractor can be either a full or half circle. A full circle is 360 degrees, based on the base-60 numerical system of the Mesopotamians, which allows the circle to be cleanly divided into six triangles, each 60 degrees. A line separating the circle in half represents 180 degrees. Further segmentation while mirroring the additional lines across the x and y-axis will create 360 evenly separated lines where each curved distance between the lines on the edge of the protractor represent a degree.


Folding a paper in half creates two lines that intersect in the middle, creating an angle with 180 degrees separation. By continuing to fold the paper in half (while keeping all sides of the paper mirrored), each new fold will create an arc along the edge of the protractor that is half the size as the previous. So, 1 fold = 180 degrees, 2 folds = 90 degrees. All angles can be determined as:


Protractors are used in fields ranging from mathematics, cartography, and physics, where the angles can be reported as degrees, arcseconds*, or radians. Degrees are for X, while radians represent Y, and arcseconds display angles on a curved surface like constellations in the sky.

*For more on arcseconds and constellations see: So, You’re Lost in Time: Determine When you Are


So, You're Lost in Space: How to Read the Pioneer Plaque

History and Composition

In 1973, one year after it was launched on February 27, 1972, the Pioneer 10 spacecraft became the first manmade object to leave the Earth’s solar system. The spacecraft was created to study Jupiter where the spacecraft would then use the immense momentum created by the gas giant to propel itself out of the solar system. Pioneer 10 is a small spacecraft, measuring in at 2.9 meters (9.5 feet) tall, only slightly taller than any unfortunate chrononaut that may find it floating in interstellar space, and it is relatively light at 258 kilograms (570 pounds). Since 1972, the spacecraft has trekked faithfully through the empty expanse of space towards the star Aldebaran—the eye of Taurus—about 65 light years away from Earth, powered by four radioisotope thermoelectric generators. While it is traveling around 11.5 km/second (about 25,700 mph) Pioneer 10 will take more than 2 million years to reach the celestial neighbor. Intended as a scientific instrument, it was known during its construction that Pioneer 10 would become the first manmade object to leave the familiar solar system for destinations unknown. In a spark of inspiration, it was agreed that in the unlikely chance it would be discovered by intelligent life, the spacecraft would be equipped with a simple greeting card from humanity. The engraving was designed in 3 short weeks by Carl Sagan, Frank Drake (of Drake Equation fame), and Linda Salzman Sagan. The 6-inch-by-9-inch (15.24 by 22.86 cm) plate is mounted externally on the antenna support structure, behind the ARC plasma experimental package. The Pioneer Plaque is 0.05 inches thick made of 6061 T6 gold-anodized aluminum plate, intended to be durable enough to endure the rough interstellar voyage. The message on the plaque is etched ~10-2 cm deep, so the symbols would remain readable even after the accumulated damage barrage of micrometeorites over the travel distance of ~10 parsecs* (32.6156 light years), and possibly as far as 100 parsecs (326.156 light years)

Hyperfine Transition of Hydrogen

To begin deciphering the Pioneer Plaque, the top left diagram is the most important as it represents the legend and “universal yardstick” that will be used throughout the diagram. Rather than any specific language, the Pioneer Plaque uses mathematics as a universal language. It could be assumed that any technologically-advanced intelligence capable of catching the spacecraft would also be familiar with some common scientific features in space, most importantly, the characteristics of hydrogen, as it is the most abundant element in the universe. The two circles represent the same hydrogen atom in different states. This symbol represents the 21-cm hyperfine transition of neutral atomic hydrogen. 

The hyperfine transition in neutral hydrogen atoms occurs when the atoms change energy states and electromagnetic radiation energy is released at a precise wavelength. The transition of these states is represented by the inverted symbols on the top of circles displaying the antiparallel to parallel nuclear and electronic spins. As a wavelength, the change in energy states can represent two potential values: a unit of length (21 cm) or a unit of time (1450 hz). This creates a legend for the hydrogen-based cipher that is used throughout the diagram. The transition between each state is connected by a line in the diagram with the binary digit for 1 below to represent this transition as a binary value. The binary values used throughout the diagram represent either the length of time value of the hydrogen cipher

Binary Translation

Binary was chosen as an interstellar language on the plaque since it is the simplest representation of numbers and can survive long periods of time under the predicted erosion caused by micrometeorites in its path along the interstellar journey. 

Binary is a base two system, where a value can either be 0 or 1. It is read from left to right, where the position of the value (n) represents the value 2n. The values for each position are multiplied by 2n and finally added together to get the final value. For example, the binary value below is 100111 represents the integer value 39:

Each string of binary values on the diagram can be assumed to be read in either direction, making the true translation slightly obscured at first glance. However, since the string of binary values are displayed in the order of most significant digits, they all start with 1 and end in 1 or 0.

For example, on the far right center of the diagram, next to the women’s figure is the value either 0001 or 1000 in binary. Since the string must start with 1, the most significant digit, the value in binary is ‘1000’ representing the integer value of 8. 

Once translated from binary to an integer value, the value is translated to its intended length value by multiplying it by the hyperfine transition of hydrogen value of 21-cm. 

8 (in binary) x 21 (cm) = 168 (cm)

The value is intended to represent the average height of women at around 168 cm (or about 5-foot-6 inches)

Solar System Diagram

The bottom diagram represents the Earth’s solar system and is perhaps the most recognizable diagram for any terrestrial travelers. The nine planets (and the Sun) present at the time of the Pioneer’s launch are represented from left to right: the Sun, Mercury, Venus, the weary and familiar sight of Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.


While each planet’s size and distance between each other is not to scale, they are accompanied by additional binary values that represent their relative distance from the Sun. These binary symbols are different from the binary values used throughout the plaque since they do not use the hydrogen cipher. This difference is indicated by the binary values being displayed as serif letters instead of sans-serif. After it has been translated from binary, the values represent a multiple of 1/10th the semimajor axis of the orbit of Mercury or 0.0387 A.U: 

integer value from binary X 0.0387 (AU) = orbital distance from the Sun

These values on the diagram would be difficult to resolve without knowing the orbit of Mercury. However, even if the distances of the solar system’s planet cannot be deciphered by an alien life, the representation of the rings of Saturn should help to distinguish the Earth’s solar system from the remaining thousands of the nearest stars that the pulsars could indicate. In addition, the small schematic of the Pioneer spacecraft indicates which planet in the diagram the craft was launched from as well the path it took around Jupiter and out of the solar system. The antenna is also positioned to point back at Earth to further clarify its point of origin.

With the combination of the 10 visible fingers and toes on each human and the use of the binary value of 10 to represent the orbit of Mercury it is also possible that this could be correctly interpreted as an indication of the Earth’s development of a base-10 counting system

How to Read a Pulsar Map with the Galactic Center

The most prominent and cryptic symbols of the plaque are the radial display on the left. This represents a display of stellar landmarks that give the position and frequency of 14 pulsars relative to the center of the maphome star, the Earth’s Sun. Pulsars are rotating neutron stars that emit strong directional jets of high energy particles. Since the stream of electromagnetic radiation can only be observed when it is pointed in the direction of the observer, as the star rotates it acts much like a cosmic lighthouse. Pulsars can be identified by their unique and predictable rotational period.

Frank Drake identified the 14 pulsars with short periods of rotation and the greatest longevity and luminosity to make them easy to identify even after long stretches of time to serve as the prominent landmarks. The pulsars are displayed on the plaque as an axial radial map with the Earth’s Sun at the center, connected by 15 solid lines that end in tick marks. Each of the 14 radial lines represent a unique pulsar’s relative distance from the Sun. The 15th line is the longest horizontal line and runs behind the diagrams of the man and woman. This line has no binary representation and represents the galactic plane and the distance the Sun sits from the center of the galaxy. This is a reference line for all the other pulsar’s distances. The length of a pulsar’s line can be compared to the length of the 15th line to gauge their relative distances compared to the distance between the Sun and the center of the galaxy. 

If the Pioneer craft is intercepted within the next few tens of millions of years—even after it has travelled hundreds of parsecs—it is likely that all 14 pulsars will still be detectable. Even if they are not all as visible, only a few pulsars are needed to triangulate the Pioneer’s point of origin. In addition, two of the Pulsars (0950 and 1929) are particularly close to the Earth’s sun, allowing the position of the Earth to be approximated to within 1 in 103 stars.

The characteristic frequency of each pulsar is represented in binary along each axial line, however since the hydrogen cipher can represent both a distance and a time, there is no direct indication which is used for the pulsars. However, since the binary values are exceptionally large, they can be assumed to be a time, rather than distance, although a smart traveler (with ample time) could try both.

integer value from binary x 1450 (hz) = Period (in units of hyperfine transition of Hydrogen)

Along the axial spokes, the string of binary numbers represent the unique frequency of the pulsar at the time of the Pioneer launch. Pulsars radiate at a regular frequency emitting electromagnetic radiation at predictable intervals and over time that frequency decreases, allowing the exact period of the pulsar to serve as a timestamp. The pulsars allow an intelligent civilization with historical records of pulsars to determine the time elapsed since the Pioneer was launched, acting as a landmark of time and space.

The tick marks near the end of each axial spoke line represent the z-coordinate relative to the galactic plane. They are also used to determine the distance from the galactic center for each pulsar. The angle between the line representing the galactic plane and the tick mark of a pulsar represents the direction angle from the galactic center. 

The distance each pulsar is shown on the pulsar map as a relative distance. The distance for each pulsar is from the center of the map to the tick mark on the line for each pulsar. The length of the 15th line for the galactic plane can be labelled as 100, so that when the length is compared to the distances for each pulsar they lie between 1 and 100.

While the map is a flat two-dimensional object, it can be extrapolated based on the polar coordinates (r, θ) of each pulsar. As a coordinate, r is the distance a pulsar is from the Sun and θ is the angle between the galactic plane and the tick mark on the end of the axial spoke. Pulsars above the horizontal line of the galactic plane are stars found above the Sun’s relative position in the galaxy (+) and those beneath it sit below the Sun along the galactic disc (-)

Human Diagrams

The plaque includes an artistic diagram of two humans to represent the starry-eyed creatures that created and launched the plaque and spacecraft. The figures, a man and a woman, were intended as a universal greeting and representatives of all mankind. 

Any meaning from the stances or features of the figures would likely be lost on any alien life, but among humans the man’s upraised hand is considered a universal symbol of goodwill and was included for want of a better symbol. However, it has the additional advantage of clearly displaying the human hand and the opposable thumb. With the ten visible fingers and toes, an optimistic writer could hope that this could potentially be a clue to humanity’s arboreal lineage and base-10 counting system. The woman stands in a different, more relaxed pose than the man, with her body weight shifted to display the flexible and mobile nature of the human body as well as the diversity among different human body types. Originally they were envisioned to be holding hands in a gesture of goodwill, but were eventually decided to be separated to avoid accidentally implying that they are a single organism. Both figures are positioned in front of a large schematic of the Pioneer spacecraft to put them in scale with the spacecraft. Whether or not the Pioneer Plaque will be discovered by alien life or curious and lost chrononauts, the plaque serves as a message to the universe from a time when humanity had first begun to take bold strides into the stars and beyond



So, You Need a Magnet: How to Build an Electromagnet


A magnet produces a magnetic field that can exert an attractive force on ferromagnetic metals like iron and steel. At room temperature, four elements are ferromagnetic: iron, cobalt, nickel, and gadolinium. Only ferromagnetic materials can become permanent magnets through various processes of magnetism.

The magnetic field is the result of the movement of an atom’s electrons. In most materials, the spin and orbit of the atoms that form the magnetic moments are pointing in random directions, so the burgeoning magnetic fields cancel out and do not produce a notable amount of magnetism. A ferromagnetic material contains aligned magnetic moments, so the magnetic field is parallel and can combine together to form a magnetic field. However, the alignment is limited to a region known as a domain, but ferromagnetic materials contain many domains. While domains form a magnetic field, they are typically randomly oriented, so most ferromagnetic materials found in nature do not normally contain magnetism.

There are three types of magnets: permanent, temporary, and natural. A permanent magnet is a magnet that is magnetized permanently and contains a persistent magnetic field. Lodestones are natural sources of magnetized materials and have been known since Earth’s antiquity by an endlessly large list of names including lightning stones or, most appropriately, magnetite. Magnetite is the raw material for steel and can become permanently magnetized when exposed to an external magnetic field. However, while magnetite behaves as a ferromagnetic metal, it is actually ferrimagnetic. Magnetite’s unique crystal structure forms two opposing but unequal polarities producing a net magnetic moment that forms its magnetic field. This is unlike ferromagnetic materials that rely on the sum of the magnetic moments of all the atoms in the material.

Magnets can come in many shapes, but each contain a magnetic north and south pole, located on opposing sides of the structure. Magnetic fields always form closed loops. To the naked eye, the magnetic field lines are invisible, but can be indirectly seen by placing a magnet in a field of iron shavings that will align parallel to the magnetic field.

Permanent magnets have the advantage that they can be found in nature and can therefore be readily used, however they also have a number of disadvantages. A permanent magnet can lose its natural magnetism in any number of ways. Most troubling while cold can strengthen magnets, heating a magnet to a high critical temperature can considerably weaken it. This is the metal’s Curie point, named after French physicist Pierre Curie in the 1800’s, and when it is reached, magnetism is eradicated. The Curie temperature for ferromagnetic materials varies (between 600-800 degrees C), where iron’s Curie point is around 700 C (1418 F) and Nickel is 354 C (669 F). Even when cooled, the magnetism remains permanently weakened. Alsopossibly more common for a traveling chrononautsharp impacts like dropping a magnet can break and randomize its internal magnetic orientation, weakening it dramatically.

The third type of magnet—a temporary magnet—depends on a fundamental principle of electromagnetism. In electromagnetism, rather than treating magnetic fields and electric fields as separate, they are intimately connected. 

It is more accurate to view magnetic and electric fields as both acting as chicken and egg. A moving magnetic field generates a current and a current generates a magnetic field. This underlying principle allows for the construction of a man-made electromagnet. A permanent magnet produces a perpetual magnetic field due to its natural properties, whereas an electromagnet is temporary since it requires a continual supply of current to form a magnetic field. However, the strength of the magnetic field can be adjusted and intensified with an increase in current and as a result often create a stronger magnetic field for the magnet’s size compared to its naturally occurring cousins.

A solenoid is a type of electromagnet created by inducing a magnetic field with current in a cylindrical coil of wire. When current is running through the wire, the closely aligned coils superimpose the magnetic field from each loop, strengthening each in turn. Solenoids can act in the same way as permanent magnets, attracting and repelling other magnets as well as attracting ferromagnetic materials like steel. The electromagnet is only a magnet as long as an electric current is flowing through the coil, allowing the magnet to be turned off and on, making it more flexible than its permanent counterpart.


The history of magnetism, and in particular, induced magnetic fields like the electromagnet, began at the very edge of the 19th century. Electromagnets require a constant current to produce a magnetic field. In 1799, Alessandro Volta demonstrated his invention of the voltaic pile, a type of battery. With this invention, physicists, chemists, and stranded chronouats had their first stable and cheap source of electric current.

Magnetism is produced by a moving electric charge, so as electrons are moved through a wire, the charged particle’s movement creates a magnetic field. In addition, a magnetic field can cause charged particles like electrons to move. The movement of charge from one region to another is known as current. 

Hans Christian Ørsted demonstrated the interconnected relationship between current and magnetic fields in 1820, only a few years before British scientists James Marsh and William Sturgeon displayed the first electromagnets to an eager audience in 1824 and 1825, eventually improved upon by Joseph Henry in the years to follow. The first electromagnet displayed was built around a ferromagnetic iron horseshoe, crudely wrapped 18 times by bare copper wire, partially insulated by shellac, a natural resin used to finish wood. The first electromagnet was only 7 ounces (.5 kg) but was capable of lifting nearly 9 pounds (~4 kg). This early electromagnet was quickly surpassed within 10 years by an electromagnet capable of carrying over 3300 pounds

(~1500 kg) by Joseph Henry. Henry had quickly outperformed the original design by experimenting with variations on Sturgeon’s original design. Most importantly, by insulating the coiled wires from one another. By preventing current from passing between the coils of bare wire, he had the opportunity to wrap multiple layers of wire around the same core, exponentially increasing the electromagnet’s power.


Electromagnets require very few supplies and no complex tools to construct. Solenoids depend on two fundamental materials: a length of insulated wire and a continuous power source. Insulating the wire is vitally important as it prevents the flow of electricity from jumping between the adjacent 

coils. The current is then forced to travel all the way through and around the coiled length of wire, increasing the strength of the produced magnetic field. Historically, before the invention of enameled wire, wires were insulated with resin and, in a pinch, even cloth with mixed results. When a wire is wrapped in a coil, each part of the wire containing current will produce a magnetic field, but in close proximity, the magnetic field lines will merge together to form a single larger and stronger magnetic field.

The magnetic field can be strengthened by increasing the current passing through the wire or by increasing the number of times the wire is coiled around the core. However, increasing the length of the solenoid will decrease its strength. In order to maximize the strength, a clever chrononaut can increase the number of coiled turns, but minimize the width of a solenoid, by stacking the coil into layers. However, it must be ensured that the layers are coiled in the same direction for each layer to avoid the magnetic fields of one layer cancelling out the fields of another.

Ampère’s Law for Magnetic Strength

β = Magnetic flux density*

μ = magnetic constant = 4π×10−7 H/m or N/Amp2

N = number of turns

I = current

   = length of solenoid

Finally, connect the two exposed ends of the wire to the source of current, most commonly a battery. Once current can flow through the wire a magnetic field will be generated. As long as the current is running uninterrupted, the electromagnet will behave functionally as a traditional permanent magnet. It will attract ferromagnetic materials, attract and repel other magnets, and contain a north and south pole. 

The strength of the magnet can be calculated based on the strength of the magnetic field, which can be used to predict the weight that the magnet will be able to support.

The right hand rule is a simple way to determine the poles of a solenoid. The direction of the magnetic field (clockwise or counterclockwise) depends on the flow of the current. 

The fingers in a fist are coiled in the direction of the coil (the direction of conventional current and in the opposite direction that the electrons are flowing) and the thumb represents the magnetic north pole of the magnet.

The force of the magnet (in Newtons) is based on the strength of the magnet, as well as the area and distance of the metal being attracted. 

So, a solenoid with 120 turns and 10 Amperes** current will produce a magnetic strength of: (120 x 10)2 (4π×10−7) = 72π/125. If the piece of metal 0.5 meters away and a cross-section of the metal’s area is 1.5 meters, then the force of the electromagnet will be:

On a planet like Earth with a gravity of 9.8065 m/s2, Newtons can be converted to kilograms of force through Newton’s Second Law of Motion where F = ma, where:

So, this magnet will be producing 0.554 kilograms of force. 

The strength can vary as the center of the coil contains the strongest and most compact magnetic field lines. Once the current stops flowing, the magnetism of the solenoid is turned off, but the metal core can still exhibit small amounts of residual magnetism.


So, You Have Scurvy: Vitamin C Deficiency, Prevention, and Treatment in a Hurry


Sanitation and proper hygiene aren’t the only aliments haunting the corridors of history. Do you have a black tongue and bleeding gums? If you haven’t been in an unlicensed temporal warp recently, these are the typical symptoms of the ancient plague of sailors and the malnourished alike: scurvy. As it lacks the ability to produce vitamin C—a vital component in the preservation and health of cells, nerves, and the immune system—the human body is destined for this prolonged and painful death without its inclusion in foods or supplements.

Causes and Prevention

The human body is incapable of producing vitamin C (C6H8O6) and as it is not stored in the human bodyinstead it is removed through the kidneys as urineit will rapidly become depleted without replenishment within a month.The anti-scurvy remedies found in ciritus* lead to the vitamin’s name “ascorbic acid” or “without scurvy” from the latin term for scurvy: scorbic. Scurvy can typically be avoided with a daily dose of 15 milligrams, but upwards to 75 and 90 milligrams are typically recommended. This is especially common when diets are limited, like those eating few vegetables, living primarily on meats and fish, and those living at sea. Prevention is distinctly diet, as the human body continually needs ascorbic acid to maintain healthy working order and it is not preserved in the tissues.


Early symptoms of scurvy include fatigue and impaired wound healing as well as dry skin and anemia. As the disease progresses, symptoms evolve to include follicular hyperkeratosisbumps of skin where hair on the body grows—and a coiling of body hair, as well as the pooling of blood in the lower body, in particular the upper thighs, giving rise to scurvy’s less common historical name “Black Legs”. As health deteriorates, bleeding becomes common from the skin, joints, and gums, leading  to scurvy’s most classic symptom: a black tongue and gums. Bleeding and swollen gums often cause loose teeth that eventually fall out. The final stages of the scurvy include the expulsion of rotten blood from the nose, stomach, lungs, and veins. Eventual death will often follow as the result of organ failure.

What Scurvy is Not

As early as the 1700’s, the source of scurvy was being narrowed down. With limited knowledge of nutrition, it was determined by firsthand accounts and research not to be an infectious or genetic disease. As scurvy is a disease described in antiquity, it is worth mentioning it is also neither a curse nor an imbalance in “humours”. While living conditions can impact an individual’s susceptibility to many diseases and recovering from illness, it will not directly cause scurvy. Scurvy is a single disease caused by vitamin deficiency, although the discovery of vitamins wouldn’t take place until 1912 with the Polish biochemist Dr. Kazimierz Funk. 

Historical Rob

Experiments in the 1700’s by a Scottish doctor proved the controlled nature of a valid cure with the use of fresh greens and citrus, long before the discovery of vitamin C. On May 20, 1747, Dr. James Lind began a six day experiment on the English ship HMS Salisbury of various antique methods of scurvy cures to determine their efficiency. Twelve scurvy patients were placed on diets ranging from meat broth, wine, elixir vitriol (sulfuric acid diluted with water), sea-water, vinegar and two lucky patients were placed on a gentle course of oranges and lemons. Among the patients, those present with citrus fruits were able to resume ship duties at the end of the six days. Among Dr. Lind’s continued experiments, oranges and lemons were the most effective treatments, with a preference for oranges that he would make into a concentrate (or “rob”) to store long-term. He considered it an infallible cure for scurvy to treat all stages of the affliction and prevent the worst of the symptoms from manifesting. While he had developed a controlled experiment to prove the efficiency of citrus fruit in curing scurvy, Dr. Lind would remain ignorant of the reason for their effectiveness, misattributing what purpose they served in the body and continuing to believe the predisposing cause was the moisture in sea air and a lazy disposition. Regardless, by 1790’s, citrus juice was issued as part of ship rations, radically reducing and oftentimes outright eliminating outbreaks of scurvy among seamen.

Cure and Treatment

Post-1900’s treatment consisted of 1 gram of vitamin C daily, for a week, split into smaller doses and consumed during meals. Should the case be caught early enough for treatment, once supplements have begun, improvement will continue over a few days or weeks, until full recovery. Untreated scurvy will eventually lead to slow agonizing death. Careful preparation of food is important, and ideally sources of vitamin C are to be eaten raw, as the heat from cooking can greatly reduce the presence of vitamin C.


*Africa: Baobab (Powder: 173 mg), Roselle Hibiscus (12 mg), Spider Plant (63 mg)

Arctic and Ocean: Kelp (28 mg), Caribou liver (24 mg), Seal brain (15 mg), Ringed Seal liver (35 mg),  Beluga Whale “Muktuk” skin (38 mg), Mountain Sorrel (36 mg)

Asia: Blackcurrant (181 mg), Kale (94 mg), Kiwifruit (93 mg), Lemon (Juice: 39 mg, Peel: 129 mg), Oranges (Juice: 45 mg, Peel: 136 mg), Limes (29 mg), Lychees (72 mg)

Australian fruit: Kakadu plum (3000 mg), Indian Gooseberry (316 mg), Cheeky Yam “Air Potato” (3 mg), Cynanchum pedunculatum (119 mg)

Europe: Rose Hips (425 mg), Blackcurrant (181 mg), Thyme (Fresh: 160 mg, Dried: 50 mg), Fresh Parsley (133 mg), Broccoli (90 mg)

Mediterranean: Thyme (Fresh: 160 mg, Dried: 50 mg), Parsley (Fresh: 133 mg), Kale (94 mg), Brussels sprouts (85 mg), Lemon (Juice: 39 mg, Peel: 129 mg)

North America: Chili pepper (144 mg), Rose Hips (425 mg)

South America: Acerola cherry (1680 mg), Chili peppers (144 mg), Guava (228 mg), Persimmons (66 mg), Papayas (61 mg), Strawberries (59 mg), Tomato (23 mg)


So, Tap Code: A Simple Grid Guide


Tap code is a simple Morse code-like method to transmit a message—letter-by-letter—with a grouped series of tapping. The alphabet is broken up into letters and organized right to left into 5 rows and 5 columns. The letter can then be transmitted by two grouped taps that designate the letter’s row and column. There is a small pause between row and column with a larger pause used to distinguish between each letter in the message. As the English alphabet by the 20th century has 26 letters to fit into the 25 spaces of the 5×5 grid, the letters C and K are grouped into the same square since they usually represent the same sound.

Tap code is simple to learn and can be taught quickly without having to fully memorize the entire grid. The first group determines the letter in the row (A, F, L, Q, or V)*, then a smaller pause before the second tap —between one and five—that determines which letter in the row. Since the letters are transmitted by row, then column, the letter R is as 4 and 2. Where, four taps for the row (A…F…L…Q) are followed by two taps for the column (Q…R). To increase readably, sentences can be further broken up by the less common letter X (5,2) in the place of a period


Tap code is typically sent as taps or knocks (also known as “Knock Code”). However, the simplicity of the code allows the messages to be sent as part of any simple grouping of signals. This includes the flashing of the lights, the beats of a drum, tapping on an arm or leg, chopping wood, whistling, or the controlled sweeping of a floor. Codes can even be stored and preserved into a physical environment with groups of knots, rocks, or stitches. 

Historically, tap code was used by prisoners and POWs during the 1900’s separated by cells. Prisoners could hold entire conversations by tapping on the bars and walls between cells. Tap code’s grid structure can be historically traced to the Polybius Square from the 150 B.C.E which used the Greek alphabet. before its adoption into English. Since physical messages can be intercepted and most codes are difficult to teach, tap code can be a simple alternative

Quick Reference

Since the messages are transmitted letter by letter, some important words can be shortened to translate quickly

SOS: (4,3) (3,4) (4,3)

Error: (1,5) (4,2) (4,2) (3,4) (4,2)

Wait: (5,2) (1,1) (2,4) (4,4)

Yes: (5,4) (1,5) (3,4)

No: (3,3) (3,4)

Repeat: (4,2) (1,5) (3,5) (1,5) (1,1) (4,4)

Ready to Receive (RTR): (4,2) (4,4) (4,2)

End of Message (EOM): (1,5) (3,4) (3,2)

Goodnight (GN): (2,2) (3,3)

Good morning (GM): (2,2) (3,2)


Numbers are transmitted in several possible ways. Numerical values can be spelled out where “2” is written out as “two”. If previously agreed upon, numbers can also be communicated by slowly tapping out the separate values where 32 is (3,2) and 127 is (1,2,7). Here, the number of zero is written as the letter O (3,4). In addition, numbers can be written 0-9 in a 6×6 grid and sent in the same method as letters


*Mnemonic for AFLQV (Always Fly Low. Quiet!—Velociraptors!)


So, Find Your Latitude by Hand: Determine Latitude at Night


A well prepared chrononaut is never lost! At least not on Earth. Latitude is the simplest form of global navigation to determine and can be estimated by hand without the use of tools. Latitude measures the (angular) distance from the poles to the equator. Each line of latitude is an imaginary line that runs horizontal around the globe with the equator at the center.

Starting at 0° latitude at the equator, moving up or down the globe will gradually increase an observer’s latitude until reaching either pole at 90° North (90° N)  in the northern hemisphere or 90° South (90° S, often written as -90°) in the southern hemisphere. The angle between the poles and the horizon form the latitude of an observer. Due to the Earth’s tilt, the poles of the planet are not considered true north or south. The true pole that is corrected for the tilt is known as the celestial north pole or celestial south pole


The open ocean lacks distinctive landmarks besides the occasional whale. Historically this meant that celestial landmarks like the moon, planets, and stars were particularly useful in determining a sailor’s position. Stars and constellations remain useful navigation tools as they move predictably in the sky during the night.

Since the position of 90°N is directly in the center of the planet’s rotation, it will not move during the course of the night. All around a pole, the stars will appear to rotate counter-clockwise. By the 20th century, it was possible to find the position of 90°N in the night sky since the bright star Polaris was within a degree of the true north celestial pole, making it a pole star. A pole star is any star close to the pole that can be used as a bright landmark to find the position of the celestial pole, and it is close enough to the celestial pole that it will not appear to move. Instead the other stars will appear to rotate in a counterclockwise wheel around it.

By the 20th century, the position of the true southern celestial pole was considerably more difficult to find. Unlike the northern hemisphere, the southern hemisphere lacked a bright star near the pole. Instead, stars rotate around the starless southern celestial pole.

However, over large periods of time, the position of all stars will change. This is due to both an individual’s star proper motion as well as the Earth’s precession. Stars are not stationary in their position and while it tends to be exceptionally small, the proper motion of stars will gradually accumulate over a few thousand years and can dramatically change the night sky. In addition, the Earth does not move in a perfect orbit, instead it undergoes a wobble in its tilt, changing the position of the Earth’s axis in the sky and as a result, where the pole points in the night sky. This wobble is known as the precession of the equinoxes.

About ten thousand years after the first moon landing (in 13000 B.C.E) the night sky will have undergone some minor changes due to proper motion, but while the star Vega will only physically move a single degree, the entire axis of rotation will shift enough that its new position will sit within a few degrees of the new true celestial north as the new northern pole star.

Precession is a cycle where the wobble of the planet’s axis changes the orientation of the Earth’s axis and over time it will trace a circle in the night sky before it returns to its original position. One complete cycle of precession takes about 26 thousand years.

A Selection of Past and Future North Pole Stars

A Selection of Past and Future South Pole Star:

To find latitude, simply compare the apparent position of the celestial pole in the sky to the horizon. A bright pole star can make finding this position easier. The angular distance between the pole star and the horizon represents the observer’s latitude within a few degrees of accuracy

Northern Hemisphere: Find the Celestial North Pole in the 20th Century

By the 20th century, the northern pole star Polaris was within a single degree of true north, more than close enough for determining latitude. As a pole star, Polaris will appear as a fixed point in the northern sky because it is almost perfectly aligned with the Earth’s axis of rotation. Polaris historically has been one of the brightest stars in the Northern Hemisphere and its position can be accurately be found using pointer stars in the Big Dipper. The edge of the cup of the Big Dipper contains two stars—Dubhe and Merak—which point towards Polaris. Polaris is almost 30° from Dubhe, which is about five times the distance between Dubhe and Merak.

At the North Pole, Polaris will appear directly above an observer at an angle of 90°. Closer to the equator, Polaris will appear closer and closer to the horizon until it drops below as an observer moves into the Southern Hemisphere where it is no longer visible.

Southern Hemisphere: Find the Celestial South Pole in the 20th Century

Unlike the Northern Hemisphere, by the 20th century, there were no remarkably bright stars in the Southern Hemisphere to serve as a southern pole star. In its place is a southern “pit”—a dark section of sky with no particularly bright stars. This “pit” still represents the position of the true south that will be used to determine latitude. However, with the comparatively dimmer stars in the Southern Hemisphere, it requires some additional work to accurately determine its position. In the absence of a true southern pole star, two methods can be used to determine the position of the southern pole’s “pit”. Both methods make use of the Southern Cross, a relatively bright southern constellation. The first uses the Southern Cross along with two pointer stars. Both the pointer stars and constellations extend a theoretical line and where they intersect is the position of the southern pole.

The second method is simpler, but perhaps more prone to user error. This method only uses the Southern Cross, and extends a theoretical line through Gacrux (the top star of the Southern Cross) and Acrux (the bottom star of the Southern cross). The distance from Gacrux and Acrux is about 6° degrees so by extending a theoretical line out four times it will intersect the southern pole

Determine Latitude

Once the position of the pole has been found, the latitude of the observer is simply the angle between the horizon and the pole. The simplest way to perform this measurement is by hand*. The width of a finger is a good approximation for 1°, a palm or fist is 10°, and an extended hand is about 25°

The closer to the equator that an observation takes place, the closer to the horizon the pole stars will appear. At each pole, the celestial poles will appear directly overhead.

A more accurate reading can be made quadrant, sextant or just a level and protractor with a hanging bob. By aiming the bottom of the protractor until it points towards the pole star, the hanging bob (pulled by gravity) will read the angle for the latitude. Lastly, to account for the design, the latitude observed by the instrument needs to be minus 90°.

A more accurate method to determine this angle can be achieved with tools like a sextant. Accuracy remains paramount to all forms of measurement. For each 1° difference from the true latitude makes up 60 nautical mile on Earth (111.12 km)


So, Cistercian Numerals


Cisterian numerals—sometimes referred to as a Cistercian cipher or Monk cipher—is an obscure medieval numeral system that is similar to traditional Hindu-Arabic numerals. Unlike the rapid widespread acceptance of Arabic numerals, Cistercian numerals were only found in a few regions of Europe during a short period of time, even during its height in limited popularity. The numerals were likely developed in response to the introduction of the foreign Hindu-Arabic math symbols into Europe by a rival religion during the early 13th century and originated in Cistercian monasteries in Hainault, London. Traditionally, the Cistercian numerals were used for numbering pages in the corners of manuscripts or displaying years rather than arithmetic, where Arabic numerals were vastly more versatile. In Arabic numerals, the value one is represented as 1, two is 2, and so on, and can represent any rational number. Unlike Arabic numerals, a single glyph in Cisterican numerals can only represent values from 1 to 9999. The system was rarely used outside of the Cistercian order and was largely abandoned by the 16th century.

Each number in the Cisterian system is broken up into a value between 1-9 and is indicated by a unique glyph built from the central stave. The units of the number (units, tens, hundreds, or thousands) are indicated by the position relative to the stave. The same shape is used facing a new direction to indicate its new digit. So, the value 5*, 50, 500, and 5000 are the same shape in four different positions. A more complex number is created by breaking apart the value into its units, tens, hundreds, and thousands and then combining them into one glyph. While zero is not defined as a value in the Cisterian cipher, the absence of a symbol is read as zero. 

Historically, most Cisterian glyphs used a horizontal stave and were read from right to left and top to bottom as units (U), tens (T), hundreds (H), thousands (K).

A vertical stave was prevalent during its brief revival in the 18th-20th century as well as in Northern France during the 14th and 15th century. For vertical staves, the values are 90° counterclockwise from how they are presented in the horizontal form and are typically read top to bottom and left to right left as units (U), tens (T), hundreds (H), thousands (K)

So, with a horizontal stave, the value 1969 is written by combining the units (9), tens (60), hundreds (900), and thousands (1000) together into a single glyph.


*In some surviving manuscripts, 5 is written as a dot (꜎) instead of a staff