Jay Phister.
Jay Phister is a North American historian who specializes in the Age of Renewal era.
In chapter 18 Sobel cites his 1952 book The Age of Renewal: McDowell at His Prime (among others) when listing eleven of Governor-General John McDowell's most important bills, which the governor-general claimed would "enable us to enter the Age of Renewal," and all of which were passed in 1883. Later in chapter 18, Sobel cites Phister's 1949 book Front Man for Reform: The Ruggles Opposition when describing Minority Leader Scott Ruggles's criticisms of the Age of Renewal legislation.
Both books appear in Sobel's bibliography.