How would dwarves tell time (calendar)

Question

Information

I am developing the culture of the dwarves in my fantasy world, and I am interested in a calendar system for my dwarves. Yes, I am aware of the question How would my dwarves tell time underground, but I was wondering how dwarves would keep track of entire years/months/days and etc.

The Criteria are:

• It must be, for the most part, independent from any other calendars.
• Not based on the sun, unless this can be worked in a interesting direction
• If based on the moon, similarly only if in a new, interesting way.

Some other Information

My dwarves revere crickets as they use them to detect poisonous/explosive gases in the mines. They keep perpetually lit forges as the draft keeps the tunnels and caves ventilated, so forges going out is bad. And they mostly eat fish, mushrooms, insects, and whatever they can trade for.

Edit: This question applies specifically to a species that lives underground (dwarves) and do not see any sunlight or moonlight, but still are affected by the outside world, in little ways, through trade and seasons. I want something that fits the dwarves specifically.

Answer 1

Based on their own biological clock. Many marine species breed during very specific times of the year, like down to a few weeks window. Mammals tend to have regular patterns for being fertile. Off spring tend to be ready to reproduce at about the same age. People sleep after so many hours awake.

So an example; dwarf short cycle is how many hours they can stay awake. The medium cycle is the time between times of fertility. The long cycle is child gestation. The life cycle is time until the next generation can reproduce.

This has the advantage of being fully unique to the dwarfs. It’ll be shaped by biology and culture and can cause issues later as culture changes (marrying age shifts by years over time, suddenly the amount of life cycles ago a king ruled is different amount of absolute time etc.)

Answer 2

There are cycles under the earth. No not bicycles!

Any repeating sequence of natural events should be helpful to your dwarves.

First thing that came to mind is rainy season. While the rain won't be falling on your dwarves heads, the water will be collecting in the mines and caves. Think of the boys trapped in the Thai caves at the moment. Authorities are worried about the oncoming rainy season flooding the caves.

If snow and ice is the source of your mines water, then spring's winter melt will be the cause of annual fluctuations in water. Even if there is no direct water source above the mines like a rainy season or snowpack you can still have fluctuations. Consider the okavango delta, which is bone dry for part of the year but then receives 11 000 billion litres of water from the Angola Highlands many miles away, not from direct rainfall over the delta itself. It takes a month for the water to travel across 1200 km of land. Now just put all that water in an underground cave system and adjust accordingly.

Secondly, as already mentioned in the comments, tide. I'm not sure how large this will be. It will typically be restricted to water sources connected to the oceans. Internal rivers and lakes don't typically have a noticeable tidal value.

Thirdly, as mentioned by Seserous, animal mating and birthing seasons. I was thinking bats, rodents, and various bugs. If there is a form of cicada in your world, you have a longer "decadal" year marker (I know, on Earth, cicadas repeat on a 7 year cycle).

Temperature doesn't seem to vary much underground, due to season.

The earth temperature beyond a depth of 1 meter is usually insensitive to the diurnal cycle of air temperature and solar radiation and the annual fluctuation of the earth temperature extends to a depth of about 10 meters. In order to study the fluctuations of the ground temperature with depth we have installed a 50m deep U-tube in the ground equipped with thermocouples at various depths. The measured temperatures indicate that the short-period temperature variations are prominent to a depth of approximately 0.5 m. Because of the high thermal inertia of the soil, the temperature fluctuations at the surface of the ground are diminished as the depth of the ground increases. The annual temperature variation of the ground at a depth of 3m is between 15 to 25°C while at a depth of 25m is negligible and the temperature remains constant at about 22°C. The temperature measurements are compared to the calculated values resulting from simulations performed with TRNSYS.

Source. PDF | Annual ground temperature measurements at various depths.

For short time-keeping, I assume some sort of water-based clock would be used. Once a standard measurement of how far a water droplet should drop is defined, they can keep track of seconds. Then they can create minutes using their number system e.g. 60 or 100 seconds etc.

They can also use the classic fantasy time-keeping candle hours based on how long it takes to burn notched candles (these are typically made of standard consistencies and have a known number of hours it will take to burn through. Although this probably is affected by drafts or trimmed wick etc).

Answer 3

Earth resonance.

from The Future of the Wireless Art, Nikola Tesla, 1908

"When the earth is struck mechanically, as is the case in some powerful terrestrial upheaval, it vibrates like a bell, its period being measured in hours. When it is struck electrically, the charge oscillates, approximately, twelve times a second. By impressing upon it current waves of certain lengths, definitely related to its diameter, the globe is thrown into resonant vibration like a wire, stationary waves forming, the nodal and ventral regions of which can be located with mathematical precision. Owing to this fact and the spheroidal shape of the earth, numerous geodetical and other data, very accurate and of the greatest scientific and practical value, can be readily secured. Through the observation of these astonishing phenomena we shall soon be able to determine the exact diameter of the planet, its configuration and volume, the extent of its elevations and depressions, and to measure, with great precision and with nothing more than an electrical device, all terrestrial distances. In the densest fog or darkness of night, without a compass or other instruments of orientation, or a timepiece, it will be possible to guide a vessel along the shortest or orthodromic path, to instantly read the latitude and longitude, the hour, the distance from any point, and the true speed and direction of movement.

The dwarves strike the earth electrically (or mechanically) using ingenious machines, and measure the vibrations. These have a characteristic oscillation. As long as the nature of the Earth is unchanged, so too the period of these oscillations does not change. Each type of oscillation corresponds to a period of dwarf time.

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Or they could use pendulum clocks. Not quite as cool, though.

Answer 4

A year, theoretically, wouldn't have to exist as the phenomena a year refers to, circling the sun, would be unknown to the Dwarves; same with a month and the moon. You might get something for seasons since that's likely to be noticed even below-ground but the smaller timeframes might not exist at all.

Given that they do presumably have the daily routine of a Human, based on the 8 hour sleep for example, they might well refer to a day as a "Cycle" with different Cycles dictating what part of the day it is. "Sleep Cycle" referring to their night, "Rising Cycle" referring to their morning, and "Mid Cycle" for the in-between.

Answer 5

Whenever I think of Dwarves I think of a race that have developed science to an artform so advanced as to appear to be magic, but I digress.

They could have a calendar based on the sun, if they had a device that measured gravity and thus pointed to the largest gravitational field. They could then discern days, years and by using different machines and measurements lunar months.

Maybe the device could, by measuring gravitational forces in a given area also then be used to help predict earthquakes, useful for subterranean dwellers.