Question: Which Earl was the Augustrus Legge, the Merton College graduate? 

Context paragraphs:
Merton College Boat Club: Merton College Boat Club (MCBC) is a rowing club for members of Merton College, Oxford.  It was established in 1838 and competes every year in Torpids and Summer Eights, the intercollegiate bumps races at the University of Oxford, as well as external regattas.

Dead Man's Walk, Oxford: Dead Man's Walk (or Deadman's Walk) is a footpath running east–west in central Oxford, England, situated immediately to the south of Merton College and just outside the old city wall, with Corpus Christi College at the western end.  To the north, Grove Walk connects with Merton Street through a gateway.  Immediately to the south is Merton Field with Merton Walk connecting to the wide tree-lined Broad Walk, which runs parallel with Dead Man's Walk.  Beyond that is Christ Church Meadow.

Augustus Legge (priest): The 5th son of William Legge, 2nd Earl of Dartmouth, he was educated at Merton College, Oxford.  A Chaplain to George III he held livings at Wonston, Crawley, Hampshire and North Waltham.  In 1820 he declined an offer to be the Bishop of Killaloe.

Merton College Library: Merton College Library (in Merton College, Oxford) is one of the earliest libraries in England and the oldest academic library in the world still in continuous daily use.  The library is located in several parts of the college, and houses a priceless collection of early printed books and more than 300 medieval manuscripts.  The historic collection was initially built through benefactions, including manuscripts donated by the medieval clergyman William Reade.  The library also contains early printed books from the personal libraries of Griffin Higgs and Henry Kent, who originally donated approximately 600 and 800 volumes respectively.  The main collection runs to approximately 70,000 volumes.

Merton College Chapel: Merton College Chapel is the church of Merton College, Oxford, England.  Dedicated to St Mary and St John the Baptist, the chapel was largely completed in its present form the end of the 13th century.

Mean speed theorem: In the 14th-century, the Oxford Calculators of Merton College and French collaborators such as Nicole Oresme proved the mean speed theorem, also known as the Merton rule of uniform acceleration, or the Merton mean speed theorem.  It essentially says that: a uniformly accelerated body (starting from rest, i.e., zero initial velocity) travels the same distance as a body with uniform speed whose speed is half the final velocity of the accelerated body.

Merton Street tennis court: Merton Street tennis court is the home of the Oxford University Real Tennis Club.  It stands on the north side of Merton Street in central Oxford, England, and forms part of Merton College.

Merton Professors: There are two Merton Professorships of English in the University of Oxford: the Merton Professor of English Language and Literature, and the Merton Professor of English Literature.  The second was created in 1914 when Sir Walter Raleigh's chair was renamed.  At the present day both professorships are associated with Merton College, but Dame Helen Gardner held her post in association with Lady Margaret Hall.  The occupants of the chairs have been:

Merton College, Oxford: Merton College (in full: The House or College of Scholars of Merton in the University of Oxford) is one of the constituent colleges of the University of Oxford in England.  Its foundation can be traced back to the 1260s when Walter de Merton, chancellor to Henry III and later to Edward I, first drew up statutes for an independent academic community and established endowments to support it.  The important feature of Walter's foundation was that this "college" was to be self-governing and the endowments were directly vested in the Warden and Fellows.

Grove Walk: Grove Walk (aka Merton Grove and Grove Passage) is a short historic leafy walkway running north–south in central Oxford, England, situated on land between Merton College to the east and Corpus Christi College to the west.  It provides one of the entrances to Christ Church Meadow from the north.

Supporting paragraphs: Augustus Legge (priest) Merton College, Oxford
Answer: 2nd Earl of Dartmouth