Galileo's Daughter

by Dava Sobel

  The lemons that hung in the garden all dropped, the last few remaining ones were sold, and from the 2 lire they brought I had three masses said for you, Sire, on my own initiative.

  I wrote to Her Ladyship the Ambassadress, as you told me to, and sent the letter to Signor Geri, but I do not have a reply, wherefore I suppose I might be wise to write again suggesting the possibility that either my letter or hers has gone astray. And here, sending you love with all my heart, I pray Our Lord to bless you.

  FROM SAN MATTEO, THE 24TH DAY OF JULY 1633.

  Your most affectionate daughter,

  Vincenzio had used part of Sestilia’s dowry to put the down payment on their Costa San Giorgio house years before. Galileo had also contributed his share then, for he was named as an owner on the deed. The house included a garden, a reservoir, and a courtyard, but its rooms were few. Now the building immediately adjacent to it had come up for sale, presenting an irresistible opportunity to expand the young family’s quarters without their having to move.

  While Galileo considered this proposal, he began to improve his health and outlook by engaging his mind in a new puzzle: Archbishop Piccolomini put him to work on the problem of recasting the giant bell for the cathedral’s campanile.

  [XXVII]

  Terrible destruction

  on the feast of

  San Lorenzo

  Sienese foundrymen had erected the mold for the new tower bell out on the street, at the foot of the tall campanile with its many-windowed tiers. The mold consisted of two clay parts— one to sculpt the outer bell curve and one the inner—nested and resting upside down inside a huge scaffold. In order to maintain the crucial spacing between the two halves, the workers suspended the great weight of the inner mold across the rim of the outer by beams, like a sieve over a teacup. But when they started to pour the molten metal, the mold’s inner section mysteriously rose and wrecked the contours of the resulting bell. Much surprise and speculation bruited through the piazza before Galileo offered the correct solution, which he proposed to reveal through a demonstration in the archbishop’s home.

  He called for an exact wooden model of the inner half of the bell mold, and when it arrived he inverted it and filled it with shot to make it heavy. Then he placed the mold model inside a glass urinal. The chamberpot cradled the bell mold, according to the archbishop’s description, “leaving between the glass and wood a space the thickness of apiastra [a heavy silver coin].” Next Galileo began to pour mercury into the urinal through a hole near the top. As soon as the quicksilver climbed just a short way up the walls of the glass container, it lifted the shot-filled mold model— though the model weighed twenty times as much as the piddling amount of mercury underneath it. Galileo had predicted this effect on the basis of his early experiments with floating bodies, wherein he showed how even a small child might lift a heavy load merely by pouring a little water.

  The same effect had undermined the casting of the bell, Galileo claimed: The liquified metal had quickly set the interior mold afloat, despite its great weight. On the next attempt, he counseled, the workers must tightly anchor the top handles of the inner mold to the pavement to prevent a recurrence.

  “And thus,” the archbishop was pleased to observe, “the second time, the casting went very well.”

  MOST BELOVED LORD FATHER

  IF MY LETTERS, as you told me in one of yours, often reach you coupled in pairs, then I can tell you, not to repeat your exact words, that in this last post your letters arrived like the Franciscan friars wearing their wooden clogs, not only yoked together, but with a resounding clatter, creating in me a much greater than usual commotion of pleasure and happiness, Sire, especially when I learned that my supplication on behalf of Vincenzio and Signor Geri, which I submitted to you, or rather urged upon you, to speak more accurately, has been agreed to and settled so promptly and with even more generosity than I had requested: and consequently I conclude that my importuning in no way posed a disturbance to your peace, for indeed that possibility had worried me greatly, and now I feel cheered and relieved and I thank you.

  As for your return, God knows how much I desire it; nonetheless, Sire, when you consider taking your leave from that city, where it has suited you for some time to remain in a place quite nearby, yet outside your own house, I should deem it better for both your health and your reputation, to stay on for several more advantageous weeks where for now you inhabit a veritable paradise of delights, especially considering the enchanting conversation of that most illustrious Monsignor Archbishop; rather than to have to return right away to your hovel, which has truly lamented your long absence; and particularly the wine casks, which, envying the praise you have lavished on the vintages of those other regions, have taken their revenge, for one of them has spoiled its contents, or indeed the wine has contrived to spoil itself, as I have already warned you might happen. And the other would have done the same, had it not been prevented by the shrewdness and diligence of Signor Rondinelli, who by recognizing the malady has prescribed the remedy, advising and working to bring about the sale of the wine, which has been accomplished, through Matteo the merchant, to an innkeeper. Just today two mule loads are being decanted and sent off, with Signor Rondinelli’s assistance. These sales, I believe, must bring in 8 scudi: Any surplus left over after the two loads will be bottled for the family and the convent as we will gladly take this little bit: it seemed imperative to seize such an expedient before the wine sprang any other surprise on us that would have necessitated throwing it away. Signor Rondinelli atttributes the whole misfortune to our not having separated the liquid from the sediment in the casks before the onset of the hot weather; something I did not know about, because I am inexperienced in this enterprise.

  The grapes in the vineyard already looked frightfully scarce before two violent hailstorms struck and completed their ruination. A few grapes were gathered in the heat of July before the arrival here of the highwaymen, who, not finding anything else to steal, helped themselves to some apples. On the feast day of San Lorenzo there came a terribly destructive storm that raged all around these parts with winds so fierce that they wreaked great havoc, and touched your house as well, Sire, carrying away quite a large piece of the roof on the side facing Signor Chellini’s property, and also knocking over one of those terracotta flower pots that held an orange tree. The tree is transplanted in the ground for the time being, until we have word from you as to whether you want another pot purchased to hold it, and we reported the roof damage to the Bini family [the now-deceased Signor Martellini’s in-laws], who promised to have it repaired.

  The other fruit trees have borne practically nothing; particularly the plums, of which we had not a single specimen; and as for those few pears that were there, they have been harvested by the wind. However the broad beans gave a very good yield, which, according to La Piera, will amount to 5 staia [less than a bushel] and all of them beautiful: now we must see to the white beans.

  It would behoove me to give you an answer concerning your inquiry about whether or not I sit idle; but I am saving that until some time when I cannot sleep, as it is now the third hour of the night. I send you greetings on behalf of everyone I have mentioned, and even more from Doctor Ronconi who never comes here without pressing me for news of you, Sire. May the Lord God bless you.

  FROM SAN MATTEO, THE 13TH DAY OF AUGUST 1633.

  Most affectionate daughter,

  Even in common parlance in a Catholic country, any day of the month could be communicated by its religious significance as easily as by its number. Thus Galileo understood the freak storm that rent his roof and toppled an orange tree to have occurred on August 10—from the mention of San Lorenzo, who met his martyrdom bound to a red-hot gridiron, quipping through this torment that his executioners should turn him over, for he had cooked enough on one side.

  The stultifying heat of the summer of 1633 oppressed the village of Arcetri. Even Suor Maria Celeste complained about the weather, for the heat always weakened h
er. Unable to sleep, she said she could barely find the strength to move her pen. This was of course an exaggeration, for she wrote her father a minimum of two letters each week, answering his call for all the minutiae of home. Occasionally she gave him news of the convent, too—of how Suor Giulia, for example, at age eighty-five, had locked arms with Death and won. But she said little of her own unflagging attention to the ailing sisters in the infirmary, or how her omni-competence positioned her as a likely candidate to become mother abbess. She might have been elected the previous December, after she had reached the proper age for holding office, but she had been strapped with her father’s concerns then, on the verge of his forced departure for Rome. Perhaps by the time of the next election, in 1635, the other nuns would look to her for the sort of leadership to be expected from one so intelligent and caring.

  Regarding the sick Sisters, the Abbess is strictly bound by herself and through other Sisters to inquire with solicitous concern about what their illness requires both in the way of counsel as also in foods and other necessary things, and so provide tenderly and compassionately according to the possibility of the situation. For all are bound to provide for and serve their sick Sisters as they themselves would wish to be served if struck down by any illness, [RULE OF SAINT CLARE, chapter VIII]

  That summer she also doctored Galileo’s servant boy, Geppo, who had spent a few days in the Florence hospital on account of a feverish illness involving his spleen. Although his youth and strength saw him quickly through this crisis, he was discharged with a disgusting-looking skin disease acquired from some fellow patient. Suor Maria Celeste cured it with an ointment of her own preparation.

  Later on in the unremitting heat, the servants ran out of flour. But since there was no question of lighting the oven anyway that August, Geppo bought bread for La Piera and himself from the convent store. It cost only eight quattrini for a large loaf, as Suor Maria Celeste informed Galileo, well in the habit now of keeping his accounts.

  Despite the heat, Galileo flourished in the favorable emotional climate at Siena. Presently he resumed work on the book he had been meaning to write for at least twenty-five years.

  He had first set down a preliminary treatise on motion while a professor at Pisa, but never published it. Then he laid new experimental groundwork for it during his two decades in Padua, where he measured the swinging of pendulums until he could describe their periods by a mathematical law, and where he rolled bronze balls down inclined planes a thousand ways to derive the rate of acceleration in free fall—in whatever time he could spare between meeting teaching obligations and running a cottage industry in military compasses. Later, as court philosopher at Florence in 1618, with the promise of more leisure for such pursuits, he reopened the labeled folders of his Paduan notes—only to be waylaid first by illness and then by comets. He returned once more to the project early in 1631, while awaiting permission to publish the Dialogue. Now, detained at the archbishop’s palace, Galileo revisited his ideas about the way everyday objects move, bend, break, and fall.

  “There is perhaps nothing in Nature older than MOTION,” Galileo noted of the humdrum topic for his next book, “about which volumes neither few nor small have been written by philosophers.” But all of those earlier texts had concerned themselves with pinning down the cause of motion. Galileo proposed to strike out on a different course—to drop all Aristotelian talk of why things moved, and focus instead on the how, through painstaking observations and measurements. In this fashion, he had discovered and described phenomena that generations of earlier philosophers had not even noticed. For example, the shape of the path traced through space by a hurled or fired missile, Galileo showed, was not just “a line somehow curved,” as his predecessors had said, but always precisely a parabola. And when lemons dropped from treetops, or cannonballs from towers, each one picked up speed in the same characteristic pattern tied to the elapsed time of its fall:

  Aristotle had ruled out any such mathematical approach to physics, on the grounds that mathematicians pondered immaterial concepts, while Nature consisted entirely of matter. And Nature, furthermore, could not be expected to follow precise numerical rules.

  Galileo argued against this stance: “Just as the accountant who wants his calculations to deal with sugar, silk, and wool must discount the boxes, bales, and other packings, so the mathematical scientist, when he wants to recognize in the concrete the effects he has proved in the abstract, must deduct any material hindrances [such as friction or air resistance]; and if he is able to do that, I assure you that things are in no less agreement than are arithmetical computations. The trouble lies, then, not in abstractness or concreteness, but with the accountant who does not know how to balance his books.”

  Manuscript page from Galileo’s book Two New Sciences

  Galileo envisioned the experimental, mathematical analysis of Nature as the wave of the future: “There will be opened a gateway and a road to a large and excellent science,” he predicted, “into which minds more piercing than mine shall penetrate to recesses still deeper.”*

  While Galileo devoted his time at Siena to writing, Ambassador Niccolini in Rome tirelessly pursued his full repatriation. The pope, however, would not be pressured into a promise, thus leaving the final sentence an open question. Rumors spoke of Galileo’s possible confinement after Siena at the Certosa, a vast hilltop monastery built in the fourteenth century to the south of Florence, where the twelve resident monks produced a locally famous wine. Such a move would bring Galileo even closer to Arcetri, facilitating the exchange of letters with his daughter, while ruling out any chance of his seeing her.

  MOST BELOVED LORD FATHER

  WHEN I WROTE TO YOU about your coming home soon, Sire, or your otherwise remaining where you are for a while longer, I knew of the petition you had made to his lordship the Ambassador, but was not yet aware of his answer, which I since learned from Signor Geri when he came here last Tuesday, just after I had written yet another letter to you, enclosing the formulation of the pills that by now must surely have reached you. My motive for addressing you in that seemingly distant fashion had grown out of my frequent discussions with Signor Rondinelli, who all through this period has been my refuge (because, as practical and experienced as he is in the ways of the world, he has many times alleviated my anxiety, prognosticating for me the outcome of situations concerning your affairs, especially in cases that seemed more precipitous to me than they later turned out to be); once during those discussions he told me how people in Florence were saying that when you departed from Siena, Sire, you would have to go to the Certosa, a condition that displeased every one of your friends; yet he saw some good in going along with those orders, as I understand the Ambassador himself did, too, for they both suspected that soliciting too urgently for your direct return here, Sire, might bring about some negative consequence, and therefore they wanted to allow more time to elapse before entreating again. Whereupon I, fearing the worst could all too easily come to pass, and hearing you were preparing to petition yet again, set myself to write to you as I did.

  If ever I fail to make a great demonstration of the desire I harbor for your return, I refrain only to avoid goading you too much or disquieting you excessively. Rather than take that risk, all through these days I have been building castles in the air, thinking to myself, if, after these two months of delay in not obtaining the favor of your release, I had been able to appeal to Her Ladyship the Ambassadress, then she, working through the sister-in-law of His Holiness, might have successfully implored the Pope on your behalf. I know, as I freely admit to you, that these are poorly drawn plans, yet still I would not rule out the possibility that the prayers of a pious daughter could outweigh even the protection of great personages. While I was wandering lost in these schemes, and I saw in your letter, Sire, how you imply that one of the things that fans my desire for your return is the anticipation of seeing myself delighted by a certain present you are bringing, oh! I can tell you that I turned truly angry;
but enraged in the way that blessed King David exhorts us in his psalm where he says, Irascimini et nolite peccare [Be angry, but sin not]. Because it seems almost as though you are inclined to believe, Sire, that the sight of the gift might mean more to me than that of you yourself: which differs as greatly from my true feelings as the darkness from the light. It could be that I mistook the sense of your words, and with this likelihood I calm myself, because if you questioned my love I would not know what to say or do. Enough, Sire, but do realize that if you are allowed to come back here to your hovel, you could not possibly find it more derelict than it is, especially now that the time approaches to refill the casks, which, as punishment for the evil they committed in allowing the wine to spoil, have been hauled up onto the porch and there staved in according to the sentence pronounced on them by the most expert wine drinkers in these parts, who point out as the primary problem your practice, Sire, of never having broken them open before, and the same experts claim the casks cannot suffer now for having had some sunshine upon their planks.

  I received 8 scudi from the sale of the wine, of which I spent 3 on six staia of wheat, so that, as the weather turns cooler, La Piera may return to her bread baking; La Piera sends her best regards to you, and says that if she were able to weigh your desire to return against her longing to see you, she feels certain her side of the scale would plummet to the depths while yours would fly up to the sky: of Geppo there is no news worthy of mention. Signor Rondinelli this week has paid the 6 scudi to Vincenzio Landucci and has retained two receipts, one for last month, one for this: I hear that Vincenzio and the children are healthy, but I do not know how they are getting along, not having been able to inquire after them from a single person.