Doomsday had been postponed. Instead, the morning of June 6 brought a clear patch through which Chappe could view unobstructed the first hints of a tiny black sphere piercing the sun's sacrosanct disk. The assembled crowd in the nearby tent now had something to see.
Henceforth no excuses remained. Heartbeats quickened as Chappe cued his interpreter inside the observatory to shout out every second of every minute on the pendulum clock. A stream of numbers cut the hush with metronomic quickness. "Cinqante-cinq minutes et un...deux...trois...quatre..."
The seven o'clock hour approached as Chappe adjusted his telescope. Like a smooth, circular pebble descending into a thick fluid, Venus began crossing the solar limb. Eighteen minutes after Venus first excited the assembled crowd with its initial appearance, the first crucial moment of its solar transit approached—when the sun had enveloped the entirety of Venus's shadow. No words the interpreter had ever said meant more to Chappe than the sequence of numbers he shouted through the observatory door. "Vingt-quatre...vingt-cinq...vingt-six..."
At 7:00 am and 28 seconds, Chappe recorded in his logbook the moment of internal contact between Venus and the sun. "I...felt an inward persuasion of the accuracy of my process," Chappe recorded. "Pleasures of the like nature may sometimes be experienced. But at this instant, I truly enjoyed that of my observation and was delighted with the hopes of its being still useful to posterity when I had quitted this life."
Many other observers of the 1761 transit reported difficulty recognizing the instant of interior contact, elongating the measure of a moment into a guessing game extended over tens of seconds. This surprise phenomenon, ruining many otherwise useful transit observations, results from an optical illusion that makes the sun's limb briefly pucker inward with a plasticity that appears to connect it with Venus's distorted disk. Chappe, on the other hand, reports no problems with what was later dubbed the "black drop effect."
The aromatic musk of Russian tea—hints of honey and Spanish pepper—spiced the air of this increasingly beneficent morning. Chappe had refused dinner the night before, and the twelve or more hours since his last meal would have left the explorer with little more than adrenaline to fuel him. The city's nobles, gathered around the nearby tent, provided a counterpoint. Spirits like bilberry wine and quas—a commonplace Russian drink made of fermented meal and malt—likely blurred these momentous few hours into pleasantry while delicacies like caviar and roasted quail tempted hungry men in Chappe's party to join in. ("All these [Siberian game] birds," Chappe grumbled, "have a disagreeable fishy taste.")
The sun continued rising, and the clouds continued to clear. Around 10:00 am, Venus had reached the halfway point in its trans-solar journey. At the exact median, Chappe tended to the second smaller telescope to make a different kind of measurement. As an independent check against the transit's time records, he also measured the separation between the nearest edge of Venus and the sun's enveloping arc. His ten-foot telescope, in less demand after drink and disinterest had peeled away some of the observatory's guests, made its 3,000-mile journey to yield one crucial number of angular distance. Inside the smaller telescope's eyepiece a translucent set of hash marks provided the ruler that yielded 6 arc minutes and 2 arc seconds of angular separation between planet and star at the transit's halfway point. And to check his check, Chappe also measured out the entire diameter of the sun: just over one-half of a degree—31 arc minutes and 37 arc seconds.
Now measured as if for a new outfit, a star ascended. It gave day to the Earth, as it always does. But on this day its closest watchers had reached into the beyond for their first grasp at a universe of knowable depth.