# Was respiratory rate used as time measurement?

There is a Jewish source that an hour was split into 1080 parts and there seems to be an explanation for that number that it is the amount of breaths taken in an hour (18 breaths per minute (which is realistic))

Is there any evidence that breath was used as a time measurement, before clocks became popular?

• Please cite all sources; context is essential to historical research.
– MCW
Commented Mar 10, 2017 at 0:45
• Presumably, when you're asking about its use for time measurement, you're talking about formal usage by a society rather than use by some hermit in a cave? Commented Mar 10, 2017 at 11:13
• "specious present" ranges from a heleq (1/18 of minute) up to tens of seconds...
– sds
Commented Mar 10, 2017 at 14:47

The human respiratory rate varies by person (and is dependent on age, health and level of exercise). According to Wikipedia, the resting range for a healthly adult would be between 12 to 18 breaths per minute (i.e. a 50% difference from low to high). For the elderly, the upper range is 10 to 30 breaths per minute (i.e. a 200% difference).

In addition, in order to measure any significant time period, you would need to stay in a resting state for the entire time while counting your breaths. It would be nearly impossible to use to measure the time taken to perform any strenuous activity because a) you breathing rate would vary and b) it would be difficult to keep a reliable track of the breaths taken. There's also the possibility that monitoring your own breathing rate would affect the rate (i.e. your attempts to keep your breathing steady might actually change the rate).

So, ultimately, it would be difficult to form a reliable universal time measurement based on something that would vary so much. It might be useful for personal use to compare a couple of events of short duration but it wouldn't be much use to pass measurements from person to person.

This made me curious, so a little searching led me to this explanation of the 1080 parts in a hour:

The division of the hour into 1080 parts can only reflect the Babylonian and Greek sources used by Jewish astronomers who did the calculations for the year. Some Babylonian astronomers used a system in which a day was divided into 360 “degrees” which were further subdivided into “barleycorns” which were 1/72 of a degree. Thus there are 72 * 360 = 25,920 barleycorns in a day. This figure was apparently adopted by Greek astronomers such as Hipparchus and Ptolemy.

The Jewish calendar calculations always subdivided the day into 24 hours. Dividing 25920 by 24 yields 1080. In other words,regardless of why any Babylonians used 360 degrees in a day and 72 barleycorns in a degree, this measure was adopted in Jewish calendar calculation.

from article here.

(I know this does not actually answer the question concerning using breath as measurement, but I thought it interesting, and answered what the real question was, which would be why the 1080 parts in an hour.)