I don't know why this detail has interested me so (other than the history buff in me) but one of the famous posters being used on the upcoming Vintage Circus Posters Stamp features the name "Hillary Long" and the fact that he was a notable acrobat famed for his being the greatest "head balancer" in the show world back in his day.
Here's the stamp (which is based almost identical to a famous circus poster featuring his stunts):

What is known is that Hillary Long died of Tuberculosis at a Tucson, Arizona Sanitorium at the very young age 45 on February 5, 1930.
About a decade ago, someone was doing some genealogical research on him but found very little about his family, not even his parents name or his exact location of burial -- as there is said to be two graves for him (one in North Carolina and another in Delaware). The known details are summarized in the link below:
http://boards.ancestrylibrary.com/l...96.1/mb.ashxInterestingly, Hillary Long actually patented some of his acrobatic equipment as shown here:


He was noted not only with Ringling Bros., but with other circus performances as well, both in the US and Australia, as described in these period newspaper excerpts:



An interesting, yet rather mysterious character, to say the least.