But we were not going to give it up so. Phoebe might have gone round the world twice before she became Io; might have gone three times, four, five, six,—nay, six hundred,—who knew? Nay, who knew how far off Phoebe-Io was or Io-Phoebe? We sent over for Annie, and she and Polly and George and I went to work again. We calculated in the next week sixty-seven orbits on the supposition of so many different distances from our surface. I laid out on a paper, which we stuck up on the wall opposite, the formula, and then one woman and one man attacked each set of elements, each having the Logarithmic Tables, and so in a week’s working-time the sixty-seven orbits were completed. Seventy-seven possible places for Io-Phoebe to be in on the forthcoming Friday evening. Of these sixty-seven, forty-one were observable above our horizon that night.
She was not in one of the forty-one, nor near it.
But Despair, if Giotto be correct, is the chief of sins. So has he depicted her in the fresco of the Arena in Padua. No sin, that, of ours! After searching all that Friday night, we slept all Saturday (sleeping after sweeping). We all came to the Chapel, Sunday, kept awake there, and taught our Sunday classes special lessons on Perseverance. On Monday we began again, and that week we calculated sixty-seven more orbits. I am sure I do not know why we stopped at sixty-seven. All of these were on the supposition that the revolution of the Brick Moon, or Io-Phoebe, was so fast that it would require either fifteen days to complete its orbit, or sixteen days, or seventeen days, and so on up to eighty-one days. And, with these orbits, on the next Friday we waited for the darkness. As we sat at tea, I asked if I should begin observing at the smallest or at the largest orbit. And there was a great clamor of diverse opinions. But little Bertha said, “Begin in the middle.”
“And what is the middle?” said George, chaffing the little girl.
But she was not to be dismayed. She had been in and out all the week, and knew that the first orbit was of fifteen days and the last of eighty-one; and, with true Lincoln School precision, she said, “The mean of the smallest orbit and the largest orbit is forty-eight days.”
“Amen!” said I, as we all laughed. “On forty-eight days we will begin.”
Alice ran to the sheets, turned up that number, and read, “R. A. 27° 11’. South declination 34° 49’.”
“Convenient place,” said George; “good omen, Bertha, my darling! If we find her there, Alice and Bertha and Clara shall all have new dolls.”
It was the first word of pleasantry that had been spoken about the horrid thing since Spoonwood Hill!
Night came at last. We trained the glass on the fated spot. I bade Polly take the eye-glass. She did so, shook her head uneasily, screwed the tube northward herself a moment, and then screamed, “It is there! it is there,—a clear disk,—gibbous shape,—and very sharp on the upper edge. Look! look! as big again as Jupiter!”