Graves described Hamilton as follows: “It may be well here to give the reader such an outline as can be drawn by memory of Hamilton’s personal appearance at this time of his life . He was of middle height, but his breadth of shoulders and amplitude of chest made him appear shorter than he really was. His head, when in social intercourse, he generally carried with an upward inclination, giving to full view his countenance beaming with an expression of ingenuous cheerfulness and receptivity. His features were not either beautiful or handsome, but there was a certain harmony in their combination which indicated strength, and in these early years produced almost the effect of good looks. His eyes were light blue; his hair was a dark silky chestnut: his nose rather broad below, the distance between it and the mouth being somewhat in excess [...]. The mouth itself of moderate size, with upper lip flexible in speaking, and slightly pouting when at rest; the chin well shaped and firm, while the breadth of the skull at its base, and its equable hemispherical development, betokened at first view a certain intellectual grandeur. He was strong and active on his limbs; his hands were soft and fair; his fingers, as has been noted by his friend Professor De Morgan, broad at the ends, and apparently not adapted for nice manipulations. Yet his manuscript, even when very minute, was exceptionally clear; and the drawing of his mathematical diagrams, which were often of great complexity, was remarkable for neatness and accuracy.” [Graves 1882, 166-167]. This description seems to be in very good agreement with the bust made around 1833.
There is another bust, made in 1830 by Thomas Kirk, which can be seen on the website of the National Gallery of Ireland. Comparing this bust with the six portraits above, it is quite imaginable that Graves preferred the 1833 minibust made by Terence Farrell. According to Graves, it was during an 1830 visit to the Dunravens, the parents of his pupil Lord Adare, that “Lord Dunraven requested him to sit to Kirk, the Dublin sculptor, for a marble bust. The request was complied with before the end of 1830; and one of Hamilton’s letters intimates the fact that, as part of he preparation for its execution, he had to submit to a cast being taken from his head. The bust may, therefore be supposed faithfully to represent his cranial development, and in this respect to possess a permanent value. In its representation, however, of the features of the face, it seems to me to be inferior as a likeness to a miniature bust executed in 1833 by Mr. Terence Farrell [...]. I have therefore preferred to prefix as frontispiece to this [1st] volume an autotype copy from a cast taken from the model of the latter.” [Graves 1882, 370].
Graves also commented on the 1859 photograph and the bust made in 1867, both shown above: “I take the opportunity of expressing my opinion that this representation of his features [the 1859 photograph] stands out from all other photographs of him which I have seen (and I believe I have seen almost all that were taken), as alone doing something like justice to the combined intellectual and moral character of the subject. It exhibits, I think, both in conformation and expression, the profound thinker, the reverent benevolent sage. The marble bust in the Library of Trinity College is from the hand of Foley, and a photograph from it supplies the frontispiece to the present [3rd] volume. Our eminent sculptor never had the advantage of seeing Sir W.R. Hamilton, and had to work from small photographs and a cast of the anterior half of the head. The aspect which the photograph presents will, however, be acknowledged by all who knew the living man to be both fine and like.” [Graves 1889, 120].
And since this is my webpage, I would like to add that, compared to the photographs and busts Graves specifically chose as representing Hamilton in the best way, the painting by Sarah Purser is not a good liking, even though I like other paintings by her very much. The problem is that in the painting Hamilton has a very different look in comparison to the six portraits and does not show what they show, precisely that what Graves called the “reverent benevolent sage.” I have often wondered whether I would have believed him enough to write my essay had I only known this painting. It can be seen on the website of the Royal Irish Academy.