Question: 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?

Answer: 
No
--

The impeachment motion had made it through a House committee, although the actual impeachment had yet to be voted on by the full House of Representatives. The latter process, as well as Nixon's trial (and almost certain removal) in the Senate, was short-circuited by Nixon's resignation.

The purpose of impeachment and trial of an elected official is the removal from office of that official. Once Nixon resigned, the purpose had been accomplished, and there was no need to proceed further in Congress.

Of course, Nixon could have been tried in "judicial" courts until the Ford pardon made that moot.
It does not appear there was any recorded appetite for that in the US House. The House Resolution ending the the impeachment committee (and commending it for its work) [passed with only 3 votes against](https://www.nytimes.com/1974/08/21/archives/house-formally-concludes-inquiry-into-impeachment-sets-out-evidence.html) it, and all 3 were strong supporters of Nixon who couldn't stomach commending the committee.

There's a good reason for this. There are two concrete ends that can be accomplished by impeachment: Removal from office, and disqualification from ever holding any other high office.

[Article 1, section 3, clause 7](https://en.wikipedia.org/wiki/Article_One_of_the_United_States_Constitution#Clause_7:_Judgment_in_cases_of_impeachment;_Punishment_on_conviction):

> 
> Judgment in Cases of Impeachment shall not extend further than to
> removal from Office, and disqualification to hold and enjoy any Office
> of honor, Trust or Profit under the United States;
> 
> 
> 

Resigning of course makes the first judgement a moot issue, but not the second.

However, in Nixon's case, he was already barred from ever running for President again, by virtue of the [22nd Ammendment](https://constitutioncenter.org/interactive-constitution/amendment/amendment-xxii), since he'd already been elected twice.

> 
> No person shall be elected to the office of the President more than
> twice, and no person who has held the office of President, or acted as
> President, for more than two years of a term to which some other
> person was elected President shall be elected to the office of
> President more than once.
> 
> 
> 

Now its still possible that he could have held some office *other than* POTUS (or VP), but that is not something ex-Presidents have historically done. So effectively, this particular judgement was moot already.

Thus, once he resigned, there was no longer any effective judgement that the US Senate could render against Nixon.

Of course an impeachment against a one-term ex-president would be a very different animal, and would presumably concentrate on getting a judgement preventing the alleged miscreant from holding office again (particularly President). Historically it hasn't ever happened, but our historical sample size here (4) is very small.