Note 1 — Chapter VI · THE JEDDAK OF LOTHAR
Reading edition
On Barsoom the ad is the basis of linear measurement. It is the equivalent of an Earthly foot, measuring about 11.694 Earth inches. As has been my custom in the past, I have generally translated Barsoomian symbols of time, distance, etc., into their Earthly equivalent, as being more easily understood by Earth readers. For those of a more studious turn of mind it may be interesting to know the Martian table of linear measurement, and so I give it here: