What is a Four Card Bob?

[EasilyFound]

Not sure where to post this, so I posted it here.

I'm trying to track down what sort of poker hand a "four card bob" is. I
know that it doesn't beat a royal flush, but is it a strong hand
otherwise? Is it another way of saying four of a kind? Here's the
context in which I found the term:

Sergeant Vance H. Marchbanks, a true hearted black soldier of the 10th
Cavalry who had been stationed at Fort Brown in 1899 wrote into the Voice
describing his experiences with the white citizens of Brownsville, the
majority of whom thought a colored man is not good enough to wear the
uniform of a United States soldier yea not good enough even to wear the
skin of a dog. In a harrowing incident, he and his female companion were
ordered off an excursion train by a Texas Ranger, brandishing a
six-shooter. Outnumbered and outgunned ? the Ranger held a Royal Flush,
while he had only a "four-card bob" and knew he could not bluff his
opponent Marchbanks obeyed.

If anyone knows anything about this arcane/archaic poker terminology and
could help me out, I'd appreciate it.