On 10 March 1855, around eight at night, a second calamitous fire struck the College. Despite the attempts by Latrobe to fireproof the building a half-century earlier, Nassau Hall was again gutted.

John Maclean Jr. , Class of 1816, now President, gave a full report to the Trustees at an emergency meeting a fortnight after the blaze. It was an accident, he told the Trustees; a piece of burning coal had landed on a carpet in a second-floor dormitory room. The occupant of the room was at Maclean's house when his room went up in flames.

Maclean noted that although the portraits in the southern pavilion had been saved, many students had lost all their possessions. He described a variety of actions taken to clear the rubble, collect the College's insurance, and shut down the refectory, now that students were boarding off campus. He also mentioned discussions with John Notman of Philadelphia, who had been brought to Princeton to "examine the walls and furnish some estimates."

A student's contemporary account of the fire

With numerous examples of Notman's work already in Princeton, the Trustees must have known what they were getting into when they hired him to remodel Nassau Hall. Under Notman, the austere Georgian building later formalized by Latrobe received several transforming elements drawn from the vocabulary of the Italianate Revival style.

Notman, like Latrobe, was constrained by having to use the original walls. This, in the words of historian Thomas J. Wertenbaker, dampened Notman's ability "to convert Old North into an Italian villa." Even so, Notman's alternations -- many of which remain today -- gave Nassau Hall a markedly different appearance.

It was Notman who gave Nassau Hall its distinctive double-arched entrance, the upper arch aggressively breaking through the Georgian pediment.

To focus attention on this new entrance, Notman eliminated the two other front doors and their pediments. The function of these entrances was now served by circular stone staircases inside towers attached to both ends of the structure.

Topped with bold Florentine turrets similar to the one on Prospect, these new stairways served at least two practical purposes. First, they cut down on the chances of a fire spreading. Second, according to Wertenbaker, they helped to "discourage the practice of 'barring out' professors by piling furniture or firewood at the top of the steps."

Latrobe's restrained, dignified cupola was replaced by the much larger and more ornate one that tops Nassau Hall today.

As a separate work of architecture, Notman's cupola has much to recommend it. It has undeniable power and clean lines. But mounted atop the Georgian-Colonial Nassau Hall, this cupola diminishes the structure rather than enhances it. It's simply too big -- a belfry suitable for a far grander building than Nassau Hall.

More successful was Notman's last major structural change, the extension of the former Prayer Hall to the south by about 40 feet. This allowed the installation of two large rounded windows on either side. The southern wall of this new space -- soon to be the new College library -- boasted a single large Palladian window. (For an architectural precedent, note the window at Andrea Palladio's famed Villa Poiana.)

This southerly exposure gave the library excellent natural light, and the space was a great improvement over the library's cramped quarters in Geological Hall.

Subsequent critics have heaped much opprobrium on Notman for the liberties he took with Nassau Hall, particularly the towers. But at the time, the Trustees were well satisfied with the transformation of Old North. As the Building Committee reported on 27 June 1860:

"With unfeigned pleasure the Committee report to the Board of Trustees that the work committed to their care is finished. Nassau Hall, burnt in 1854 [sic], has not only been rebuilt, but has been enlarged and greatly improved. It is in every respect a better building than it ever was before: and it is the belief of the Committee that a more substantial and commodious college building is no where to be seen in our country. Its walls are stone and brick, its roof iron and slate; its timbers iron with arches of brick between them all. It contains fifty-four lodging rooms for the accommodation of the students, with ample provision for heating, ventilation,&c. The Library Room is large, beautifully proportioned, and chastely furnished."

In the years immediately following the second great fire, President Maclean was forced to operate the College on a tight belt. Donations to rebuild Nassau Hall were not as forthcoming as they had been in 1802, and for five years Maclean struggled to pay off the College's debt.

This was just a taste of greater struggles to come, however. Matriculating freshmen moving into the newly renovated Nassau Hall in the fall of 1856 could scarcely have imagined that by the time they graduated, the country would be on the brink of the most violent and bloody upheaval in its history.

Doubtless the election of Lincoln and threats of secession weighed heavily on the minds of the Trustees when they met in December 1860, scarcely six months before the Battle of First Manassas. On their agenda were proposals to raise two new structures. The first, the new Cloaca Maxima, would resolve once and for all the nettlesome "backbuilding" issue.