Green’s Dictionary of Slang

a schoolteacher, esp. a pedant; thus gerund-grinding, instruction in Latin grammar, pedantic instruction generally; gerund-stone, the imaginary grindstone of a gerund-grinder.

1759–67		Sterne Tristram Shandy (1996) 276: Tutors, governors, gerund-grinders, and bear-leaders.
1788		V. Knox Winter Evenings 59: A pedant, a mere plodder, a petty tyrant, a gerund-grinder [F&H].
1825–7		W. Hone Every Day Book II 33: Gerund-grinding and parsing are usually prepared for at the last moment [F&H].
1832		Spirit of the Times (NY) 11 Feb. 2/1: A ‘village schoolmaster,’ a ‘country grammar grinder’.
1837		Morn. Chron. (London) 4 Jan. 3/6: That stout-built gerund grinder, the Rev. M. Monk.
1840		Era (London) 3 May 8/1: It is certainly not he who has the soundest views on [...] the value of education, who will be most inclined to respect the birch-wielding gerund-grinder.
1858		Hereford Jrnl 13 Oct. 2/2: Yours, a Quondam Gerund-Grinder.
1867		Pall Mall Gaz. 25 Oct. 3/2: The master degenerates into something worse than a gerund-grinder.
1870		Manchester Courier 20 Jan. 5/1: If a master is to rise above the level of a ‘gerund-grinder’ he ought to possess many qualifications.
1886		Morn. Post (London) 6 Nov. 5/2: The ‘Gerund-grinder’ [...] maye be tolerated [...] so long as side by side with them we find men of brilliant parts.
1890		Music Hall & Theatre Rev. 1 Nov. 5/2: The Catherine Street grammar grinder startles us with the information that [etc].
1897		Leeds Times 5 June 4/3: Public school masters ought to [...] think themselves fortunate with [...] the annual holiday which falls to the lot of the ‘tired’ gerund-grinder.
1913		Aberdeen Jrnl 30 Dec. 5/3: If he were a mere instructor, the gerund-grinder [...] a mere mnachine for filling the minds of children [etc.].
1945		‘Campus Sl. at Minnesota’ in AS XX:3 Oct. 233/1: Her gerund grinder is known as the Ph.D. demon or comma hound.