The year 1910 brought major changes to the building and to Northumberland Unitarians.  Rev. Haskett Catlin, back in town,  emerged from retirement and resumed regular weekly services. The few remaining Taggarts and Priestleys deeded the building over to the American Unitarian Association (AUA) to preserve as a memorial to Joseph Priestley, and extensive repairs and renovations were made. A basement was dug, a coal furnace installed, and subsequently a loft added for the organ.  By this time the shutters had already been installed as evidenced in a photo taken about 1910 by Nelson F. Davis.(1) This is probably when the present sanctuary was built, as evidenced by the kerosene lamps which flank the pulpit; kerosene was not developed until well into the last half of the 19th century.  Further, it has been reported that the potbellied stove still occupied that space in 1909.

On Oct. 24, 1910, representatives from the AUA and from Unitarian churches in several states convened at the chapel and rededicated it as the “Joseph Priestley Memorial Church”, but the interior makeover was not completed until 1912 when the stained glass windows were installed on either side of the pulpit.  One window  was the gift of the Priestley sisters and honors their father, Joseph Priestley, MD (great-grandson of JP). The other window, a gift of the Misses Mary and Anna Taggart, honors the doctor's wife and their aunt, Hannah Huston Taggart Priestley.  The shutters for those windows were removed, probably because they hid the tops of the windows.  Rev. Catlin reported an average attendance of 25 persons in the beginning, but the renaissance was soon over. With the oncoming war, attendance dropped off and in 1917 Catlin’s death brought an end to services once again.