I sorry that it has taken me almost 4 years to notice this question. The Biffar name only appears breifly in the extensive research that my father's cousin, Janice (Grosbouer) Miller, has performed on the Silkworth family. The notation is that Lain's city directory "Brooklyn 1876" indicated a Biffar studio at 113 4th St., Brooklyn, N.Y.
Amos married Mary Biffar, and appears to have been awarded the Biffar studio. The only address I can recall from my grandfather's momentos was the Broadway, Brooklyn address (307? as I have seen here). It had the scripted Silkworth logo only. (My childish mind confused this with a more trendy Manhattan location.)
Unfortunately, Mary Biffar died (reportedly following childbirth) on 25 March 1886. Amos continued to run the photograpy studio in his name for some 15 years (or so) afterwards. He married my greatgrandmother in 1888, so the Biffar record ends for us. The surviving child from the Silkworth-Biffar marriage was Amos Worthington Silkworth. My greatgrandfather referred to him "Worthy" and cherished him in remembrance of Mary no doubt. I knew him as "Uncle Doc". Uncle Doc lived as a batchelor his entire life. As far as I know that would be and end point on the Biffar family tree.
There is a notation regarding Lain's "Brooklyn 1893" which listed a Silkworth photograpy studio (Amos Wood Silkworth and Albert Charles Silkworth) at 261 Manhattan Avenue, Brooklyn, N.Y. Apparently this was also the home address of a Silkworth cousin, Charles E. Silkworth, Jr. I don't know what to read into this.
It seems that photography was the "high tech" field of the day, and must have been quite lucrative. Amos purchased a marvelous spread on the Long Island sound in Mattituck, N.Y. around the turn of the century. Alas, "The Old Homestead", as my grandfather would recall it was lost to creditor's during the Great Depression.
Amos became seriously ill by 1910 and returned to commercial photography working for others, I believe this was in New Jersey. He died in 1917 in Southold, which is close to the "Homestead" location. Many of my father's relatives had connection to Southold. There is a graveyard there where many rest. I recall as a child running through the site (with some slightly older "cousin" relations), which was just beyond the back yard of one of my father's cousins,from his mother's side, Albert Conklin (I really favored "Uncle Al").