[kragen]

    kragen@inexorable:~$ units
    2411 units, 71 prefixes, 33 nonlinear units

    You have: 4 score hogshead moons per gross of firkin
    Unknown unit 'moons'
    You have: 

Were you thinking lunar months, moon masses, moon radii, moon apogee...?

[pbhjpbhj]

I was thinking "moons" as a period of time, so a lunar month : [time][volume]/[volume]

As in "We'll see 3 more moons before yon mountain dons his snowy cape." or some such yokel-ese.

[kragen]

Well, fourscore hogshead per gross of firkin is 3.8̄ (i.e. 35/9), so fourscore hogshead-moons per gross of firkin is about 115 days.

[pbhjpbhj]

It was intended as a witty remark, I only parsed for unitary conformance not for value and didn't bother to answer the question.

Perhaps you'd like to do it and provide the answer in these units?