Time can be measured in days, months, years. The ultimate time measures are fractions of days.
The number 10 is based on counting ones fingers
The numbers 28 - 30 are probably based on estimates of the moon cycle; 360 on the length of the year and approximately twelve moon cycles, i.e. months. Some peoples of very early times used 366 as the number of sunrises in a year and therefore using a circle as a representation of a year dived the circle into 366 parts.
Distance is easily measured with a stick or rod; the most portable distance measuring device is a length of some flexible material like a length of vine, twine, rope, or chain, etc.
The easiest and most portable length measuring standards relate to body parts, the hand, foot, arm, etc.
Ancient Astronomical Measuring Devices: Vertical Rod or gnomon, properly ls a set of steps or stair.
The best representation of a cycle is a circle. Of the many cycles we experience are: the day, month and year. Some number of these forms a person's life. Life itself follows a cyclic pattern and becomes what tends to be called a life cycle usually now measured in number of years. This number seems to be increasing if you live in a well run contemporary society, and are lucky. I am an octogenarian which signifies at least 80 complete years. A short time in relation to recorded history, and very short in terms of the postulated age of the earth, universe etc, however relatively long in terms of the ages of my male ancestors.
Why 360 degrees
in a circle?
My speculation is that in the distant past people noticed that the yearly cycle repeated itself and became curious as to how many days formed the year. One recorded each day with some kind of marker. You could do it as a line or some other way of arranging the markers. When a new year was detected, i.e. the cycle started over again a logical approach would be to start at the beginning and repeat the cycle. The easiest figure to follow for this is circular. A good approximation of the length of the year is 360 days and the ideal pattern for keeping track of the progress of the year is a circle. In the book 'Uriel's Machine' it is mentioned that the year was for a while thought to consist of 368 nights so 368 days was used. It takes on a few years to find out that 366 days and nights is a better approximation. Since 366 is an awkward number, one can imagine simplifying things by using 360 with and error term of 5, or 6. Many world calendar advocates still think in terms of a 360 day year with five world days added to make it nearly correct. If the extra day is added every fourth year we arrive at the current calendar. The leap years are used to correct the cycle time for y area to what it really is, rather than the number 365.
It is easier to count lunar cycles and to count the days in a month.
Quarter points of Year
Repeated observation of the yearly cycle will reveal that there are four special times: shortest day, days when there is equal daylight and dark and longest day. Depending on your thinking one of them can be chosen as the beginning of a new year. At present we use the period with the shortest day. We don't use the shortest day because of calendar errors in the past. Similarly Easter is related to the transition from when there is more dark than daylight hours to when the light begins to exceed the dark. This has been used in the past as the time of the New Year. It is approximately when the plants begin to grow again and a time for planting
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