# Tag Info

Accepted

### How did Ptolemy know that days were unequal lengths?

You are right: at the time of Ptolemy they could not measure the length of a day directly. Actually Ptolemy never discusses any clocks in his book, he probably used some crude devices record the ...
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### Why historically the hour was divided into 60 minutes and when it had started?

It comes from the ancient Babylonian numeration system which had base 60. (The reason for the choice of such a base is simplicity of calculation: 60 is divisible by 2,3,4,5,6,10,12,15,20,30. Much more ...
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### How did people count seconds before clocks were invented?

Electricity has nothing to do with the question. Clocks which could count minutes and seconds were purely mechanical and precise mechanical clocks (which could count seconds reliably) were invented in ...
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### Was there ever a proposal for Metric time

The French Revolution introduced a decimal clock, where the day was divided into 10 "hours" each, these hours into 100 minutes, and these minutes into 100 seconds. The clock looked like this: https://...
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Accepted

### Where did the popular idea of spacetime come from?

A nice history was given by Archibald, R.C. (1914), "Time as a fourth dimension", Bull. Amer. Math. Soc., 20 (8): 409–412 https://doi.org/10.1090%2FS0002-9904-1914-02511-X Regarding Wells, ...
• 431

### When were clocks used for the first time in science?

Water clock is also a kind of "mechanized clock", and it can be very sophisticated. There is a strong evidence that in ancient Babylon and Greece they were used in science, namely for ...
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### How did people count seconds before clocks were invented?

How did people count seconds before clocks were invented? In general, they didn't, because there was no need to to so. The need for accuracy to the level of a second or less is a very recent need. ...
• 1,717
Accepted

### Did English ever use a third (1/60 of a second) for measuring time?

Right after your quote Wikipedia has "In 1267, the medieval scientist Roger Bacon, writing in Latin, defined the division of time between full moons as a number of hours, minutes, seconds, thirds, ...
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### Have there been accurate alternative clocks/ways to tell time?

French Revolutionary time had ten hours to the day, 100 minutes to the hour, and 100 secnds to the minute. That same article describes a couple of other instances of decimal time.
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### When and on what basis was it decided that an hour have 60 minutes and a minute have 60 seconds?

The use of a base 60 number system in Babylon is mentioned at http://www.storyofmathematics.com/sumerian.html where it says, "Sumerian and Babylonian mathematics was based on a sexegesimal, or base 60,...
Accepted

### Is there another calendar with the equivalent of gregorians weeks?

The French Republican Calendar, actually used for a time in France... LINK The weeks were 10 days each, called "décades".
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Accepted

### What did Galileo's "pulsilogon" look like?

According to the medical journal article The History of Instrumental Precision in Medicine, referring to the pulsilogon : Unclaimed by Galileo, it was attributed to Paolo Sarpi, and clearly enough ...
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### Why does the start of the calendar year not correspond to a natural event?

Because the various "calendar modifications" in Western Europe during the ages were driven by political and religious "interests" and not by scientific ones. European calendar is ...
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### Did English ever use a third (1/60 of a second) for measuring time?

Oxford English Dictionary third, adj. (and adv.) and n. Definition B.7.a. The third of the subdivisions of any standard measure or dimension which is successively subdivided in a constant ratio; the ...
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### When and how was it discovered that the sun was in different positions depending upon longitude?

This is an immediate logical consequence of sphericity of the Earth. Greek tradition credits sphericity to Pythagoras, but modern historians even doubt that he ever existed. So the question has no ...
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### Did Weizsäcker's change his mind about time being a fundamental object?

Weizsäcker did not change his mind and continued to develop "temporal logic" until 1990-s (e.g. in Zeit und Wissen, 1992). It is central to his general idea of the relationship between logic and ...
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### What is the historical basis for the length of a sidereal year?

By looking at stars position with respect to the point of intersection of the ecliptic and equator (this is a position of the Sun at the equinox). Or which is the same at the position of this point ...
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### Why were extremely accurate sundials necessary in India?

Indian and Chinese calendars are astronomical, in that for instance dates are based on the exact moment of astronomical events. So wheter for instance a new Moon falls one second before or after ...

### Why were extremely accurate sundials necessary in India?

The Jantar Mantar monument in Jaipur was built on the orders of the Rajput king Sawai Jai Singh II, and completed in 1734. Aside from the sundial it has an observatory with various other instruments ...
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1 vote

### How did people count seconds before clocks were invented?

They didn't. The first person to divide time into 24 hours/60 minutes/60 seconds was the scholar al-Biruni (973 - ~1050) who lived in what is now Uzbekistan. He invented the concept in about 1000 as a ...
1 vote

### Were people in the ancient or medieval times aware of how exactly a solar year is equal to a lunar year?

Hipparchus, who lived in the 2nd century BCE, calculated the length of the synodic lunar month as 29.53059 days, and that of the tropical year as 365.24667 days (though he expressed both values not in ...
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1 vote

### Was there ever a proposal for Metric time

EDITED. To add some more information to fdb's answer. They divided the day+night period into 10 hours, so their hour was more than 2 of our hours. They also introduced decimal units for angles (which ...
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