Also under consideration before the Civil War was a proposal to build an observatory. Having secured the students' most basic need-- lodging -- the College could once more explore the possibility of constructing a specialized building for academic purposes.

Long championed by the astronomer Stephen Alexander , one of the College's most distinguished professors, a new observatory (with a superior telescope) would establish the College as a leader in the field. So thought Alexander, and he proved a resourceful fundraiser in this cause. One patron in particular -- Colonel Nathaniel Halsted, of Harrison, New Jersey -- had as much as promised to underwrite the observatory shortly before the war.

When a colleague of Alexander's died late in 1860 and left the College a $2,500 legacy for an observatory, Alexander must have felt on the verge of triumph. But suddenly Alexander's other sources of funding evaporated.

As the minutes delicately noted, "For some weeks the state of things in the country has been such as to render it inexpedient to make the proposed [fund-raising] application to the friends of the College, and of science, for funds." The observatory was shelved for the duration of the Civil War.

Thanks to the unflagging energy of President Maclean, the College managed to stay open throughout the war. But certainly nothing as extravagant as a new building could even have been contemplated under the circumstances. Thus it was not until December 1865 that the College looked to build again.

At the top of its list stood the observatory put on hold in 1860. Fulfilling his commitment, Halsted, now a general, presented the College with $10,000 in United States bonds for this new structure.

Professor Alexander quickly took charge of the building committee, and one of his first acts was to add Halsted to the committee. By June 1866 he was able to show plans to the Trustees. Again, no architect was formally commissioned to design the observatory, but a well-respected and "competent" German architect from Newark had been consulted. The builder from Newark estimated the cost of the building at $18,000, which Halsted agreed to provide.

Perhaps the builder's influence explains the three distinctive domes, the largest of which covered the telescope. Built of metal and stone from the Prallsville quarry, the Halsted Observatory stands at something of an architectural turning point on the campus: It was the first structure to show signs of the Victorian Gothic style that would dominate the Princeton campus for the next three decades, but its roots were still firmly grounded in the context of the other College buildings.

At this same June meeting, the Trustees approved the purchase of two lots on the extreme western end of the campus as a site for the observatory. The cornerstone was laid two days later.

The project was plagued by delays. The foundations for the central pier (which would support the telescope) had to be sunk 18 feet below the surface before finding bedrock; this pier eventually measured more than 40 feet long and contained some 23,000 cubic feet of stone. A year after construction commenced, the building was nowhere near complete, and its most important accoutrement -- a 30-foot-long telescope with a 23-inch aperture -- had not yet been manufactured.

When Maclean resigned as President of the College in December 1867, the observatory was still under construction. But the promise inherent in this unfinished structure would help entice Maclean's successor as President from his native Scotland to Princeton. Halsted Observatory was the first building completed in the long and immensely productive administration of James McCosh.

Halsted Observatory marked another watershed in the evolution of the campus. Reflecting a change in social mores, it was the first building at the College explicitly named for the donor. In the past, such vanity would not have been countenanced. After the war, however, a new class of philanthropists emerged who were very interested in having structures -- even entire institutions -- named for them.

McCosh was a savvy administrator and leader, and he knew a potential source of funds when he saw it. Halsted Observatory might have been the first building on the campus named for the donor, but it would not be the last. Fueled by private donations, McCosh ushered in a construction boom unprecedented in the College's history.