Jerome de Lalande's Ladies Astronomy

A translation of Lalande's Astronomie des dames (1785) from French to English was made by Mrs W Pengree and published as Ladies Astronomy in 1815. Below we give the Historical Preface to that work.

Historical Preface.

The spectacle of the heavens is an object of such general interest, that it ought necessarily to form a part of every regular course of instruction. We accordingly see ladies taking a lively interest in it, putting questions on astronomical subjects, and regretting their inability to pursue its study. But it is very difficult to acquire any adequate knowledge of the science, without diagrams and calculations: I shall, therefore, in this work give only a general picture of astronomy, and the great phenomena which it presents; with the curious discoveries made by astronomers, and the means by which they have arrived at conclusions, so surprising to those who have not acquired the first rudiments.

Confining myself within these limits, I cannot refer to my large Treatise on Astronomy, (in three volumes quarto,) nor to the Abridgement, (in one volume octavo,) as even the latter would require some previous knowledge of geometry and mathematics, which I have thought best to avoid in this work. Perhaps I ought to have given the first elements of the mathematics; but I feared it might appear too complicated for the generality of those for whom this work is intended, and whom it is my wish not to discourage on the borders of the science.

The Plurality of Worlds, by Fontenelle, published in 1686, which is still very generally read, might, perhaps, have served me for a model; omitting only the hypothetical and obsolete, (such, for instance, as the vortices,) and correcting some errors, which must be visible to everyone, particularly in his observations upon comets. But that work does not enter sufficiently into the subject; and, with whatever attention it be read, but a very imperfect idea of the constitution of the heavens will be obtained.

I shall begin this treatise in the same method I adopted in my larger work; because, after mature consideration, I cannot find any thing more suitable to the object I have in view: requesting only from my fair readers, (after the example of Fontenelle,) "that degree of application which they would find necessary in perusing the Princess of Cleves, if they are desirous of becoming acquainted with its beauties." It is true, that the subject of this treatise may not be so familiar to them; but it is not less intelligible, and I am confident that, after a second reading, at most, it will be perfectly understood.

My object, however, is different from that of Fontenelle, who was desirous of bringing astronomy to such a point, as would neither be too dry for the generality of his readers, nor too trifling for the learned. But, as he himself says, that, by seeking to adapt this science to everyone, it might be found suitable to no one, I shall devote this work exclusively to the ladies.

We have, already, many instances of females, who have evinced a laudable spirit of inquiry, and great perseverance in the pursuit of this science. The beautiful Hypatia, who was assassinated by the clergy at Alexandria, in the year 415, taught astronomy there, and composed several works. Maria Cunitz, the daughter of a physician of Silesia, published some astronomical tables in 1650; and Maria Claire Eimart Muller, the wife and daughter of two well-known astronomers, was also well versed in this science. In 1680, Joanna Dumée gave lectures on the Copernican system; and the wife of Hevelius made observations with him. Manfredi's sister calculated the Ephemeris of Boulogne; as did Kirch's three sisters, for a length of time, that of Berlin: his wife, also, published, in 1712, a work on astronomy. The Marchioness du Chatelet translated and published the works of Newton; and the Countess of Purinina, to whom the passage in Scripture, "Una mulier fuit confusionem genti," was justly applied, founded an observatory in Poland. Madame Lepaute, who died in 1788, calculated the ephemeris of the Academy for more than ten years; and the widow of Mr Edwards is now employed in England, in the composition of the Nautical Almanack. Madame du Piery, the first lady who taught astronomy at Paris, made several calculations of eclipses, to ascertain the Moon's motion; and Miss Caroline Herschel, whose proficiency in the science is so well known, has discovered five comets. Madame la Duchesse de Gotha does not wish to be quoted, but she has, likewise, made several calculations; and my niece, Françoise de Lalande, assists her husband in his observations, whence she draws her conclusions by calculations. She has reduced ten thousand stars, and has published three hundred pages of Horary Tables for the Navy; an immense work for one of her age and sex, which may be found in my Abridgement of Navigation.

We have here given sufficient instances of females who have distinguished themselves, even under every disadvantage of education and prejudice, to convince us that their abilities are not inferior, even to those of our sex who have attained the highest celebrity in the sciences.

The utility of astronomy, independently of the sublime spectacle which it presents to us, and in which all well-informed persons take an interest, is so generally acknowledged, that it requires but little comment. By the aid of astronomy, geography and navigation have united the furthest extremities of the globe; and by its means, the calendar and chronology have been regulated, sundials constructed, &c.

The return of the seasons and meteorological predictions may, hereafter, become a very important object of astronomy, but they are as yet imperfectly understood. There is reason, however, to believe that a similarity of seasons, as well as eclipses, returns nearly every eighteen years; an idea of which I have sometimes availed myself, with success, in the Paris journals, to satisfy the public mind on the apparent uncertainty of the seasons.

We have, in history, many instances of the ill-effects of ignorance in the science of astronomy as experienced by whole nations. Nicias, an Athenian general, having determined to quit Sicily, was so dismayed at an eclipse of the Moon, that he suffered the favourable moment to escape him, and his own death, with the ruin of his army, ensued: an event so fatal to the Athenians, that it is from that period they date the decline of their power. Even the troops of Alexander were thrown into the greatest alarm, by an eclipse of the Moon, before the battle of Arbela, of which he sent to acquaint the Egyptian astronomers, and commanded sacrifices to be offered to the Sun, the Moon, and the Earth, as divinities who had occasioned the eclipse.

We find, on the contrary, other generals, to whom the knowledge of astronomy proved particularly useful. When Pericles commanded the Athenian fleet, there happened an eclipse of the Sun which occasioned general consternation. The pilot himself trembled; but Pericles removed his fears by this very simple comparison: covering the pilot's eyes with the end of his cloak, "Thinkest thou," said he, "that what I now do is a sign of misfortune?" "No, certainly not," replied the pilot. "And yet," resumed Pericles, "this is an eclipse to thee: it differs from that which thou hast seen only in this - that the Moon, being much larger than my croak, hides the Sun from a greater number of persons."

Agathocles, king of Syracuse, during a war in Africa, perceived, at a critical moment, that terror was widely spreading through his army at the sight of an eclipse; but, presenting himself before his soldiers, and explaining the cause of this alarming phenomenon, he succeeded in dissipating their fears.

Tacitus, also, speaks of an eclipse, of which Drasus availed himself, to appease a revolt. And instances of this kind are mentioned of Sulpitius Gallus, a lieutenant of Paulus Emilius, in the war against Perseus; as also of Dion, king of Sicily. Christopher Columbus, likewise, when at Jamaica, taking advantage of an eclipse of the Moon, which he knew would happen, compelled the savages to deliver him from a very critical situation; and I have myself been frequently enabled, by my knowledge of astronomy, to relieve the public mind from those terrors, which the predictions of astrologers, and the appearance of comets, have but too frequently occasioned. In 1186, there was a conjunction of all the planets, which, it was said, portended unheard-of calamities; yet no extraordinary event signalised that year. In 1773, the Parisians were thrown into the greatest alarm, from the expectation of a comet, for which there was no foundation; and this inconceivable panic extended even to other countries.

Having given some idea of the utility and advantages of astronomy, we will consider the history and progress of this science. According to Mr Bailly, the origin of astronomy may be traced to an antediluvian people, now forgotten, but from whom some fragments of astronomical information have been preserved. Other historians ascribe it to the Egyptians and Chaldeans. It was in Egypt that Plato and Eudoxus conceived those ideas with which they enriched Greece, 370 years before the vulgar era; and Cepheus and Cassiopeia, were natives of Ethiopia, which fixes the origin of the constellations in the south of Egypt. But the Egyptians carefully concealed their knowledge; all traces of which were lost with their government, religion, and language. It was among the Babylonians, that Hipparchus found the most ancient observations of which he could avail himself, to determine the Moon's motion. The first of these is an eclipse of the Moon, observed at Babylon 721 years before the Christian era; and Ptolemy preserved many others, up to the year 492 before our era, after which period, the kings of Persia becoming masters of Babylon, and not residing there, less emulation was excited, and the reputation of the sciences consequently declined.

The Greeks say, that Thales, of Miletus in Ionia, about 600 years before our era, was the first who determined the Sun's motion, and taught the Greeks the cause of eclipses. Herodotus even asserts, that he predicted an eclipse; this, however, he could have done only from his knowledge of their regular return every eighteen years which he must have acquired either in Egypt or Chaldea. About 300 years before the Christian era, a revolution took place in astronomy, under the protection of the Ptolemys, kings of Egypt. The first Greeks who cultivated this science at Alexandria, were Timocharis and Aristillus. Ptolemy, in his Almagest, assures us, that Hipparchus had availed himself of their observations, imperfect as they were; and that he had, by their means, discovered the movement of the stars in longitude. Ptolemy himself quotes many of their observations; the most ancient of which was in the year 294 before our era. Timocharis saw the northern edge of the Moon, touch the northern star in the brow of the Scorpion. This observation is one of the best, of which we can avail ourselves, to determine the motion of the fixed stars.

Ptolemy Philadelphia succeeded Ptolemy son of Lagus, about the year 283. He was a prince well versed in the sciences, and the avowed protector of all those by whom they were cultivated. He invited the learned to his capital, not only from Greece, but other countries; appropriated apartments in his palace to their use; assigned them an honourable provision; and thus furnished them with the means of applying themselves successfully to the sciences. The Museum or College of Alexandria, is celebrated by Strabo. The emulation which prevailed at that period in Egypt, still existed at the time of the invasion of the Saracens, in the year 634 of our era; though the sciences had greatly declined, even since Strabo's time, who lived in the reign of Augustus.

Aristarchus of Samos, about 264 years before the vulgar era, taught the motion of the Earth round the Sun, of which, however, Philolaus had spoken before him. He conceived an ingenious method to find the distance of the Sun from the Earth, by supposing that of the Moon to be known, which is, in fact, the easiest to ascertain.

Eratosthenes, born at Cyrene, 276 years before our era, was invited by Ptolemy Evergetes, from Athens to Alexandria, where he was appointed to superintend the royal library. By his direction an armillary circle of bronze, or a great circle in the form of a ring, was erected in the Portico, with an inclination corresponding to that of the celestial equator, to ascertain the exact time when the Sun was in the equinox. Hipparchus availed himself of it, in the following century, in making his observations, which are still considered very valuable.

Eratosthenes was also the first who attempted to measure the circumference of the Earth.

Hipparchus appeared at Alexandria about the year 160 before our era. He was the most intelligent and indefatigable astronomer, whose name tradition has transmitted to us. Real astronomy may be said to have begun with him: he collected the most ancient observations, to which he added many of his own; and having discovered that the motions of the planets were not uniform, he even determined their irregularities, at least as regards the Sun and Moon, and ascertained the true length of the year. He also rectified the measurement of the Earth, as given by Eratosthenes.

Having discovered a new star, which appeared in his time, and being persuaded that these phenomena might frequently occur, and that those stars might have a motion which are reputed fixed, he, as Pliny expresses it, "by a godlike enterprise, transmitted to posterity the enumeration of the stars of heaven; whence, having ascertained their situations, with instruments of his own invention, by which he was enabled to mark their places and magnitudes, he afforded the means of discovering, in future, whether any stars disappeared, and became again visible; or if they changed their situations, magnitudes, or light. Thus, as it were, leaving the heavens as an inheritance to all those who were capable of profiting by the gift."

This catalogue of Hipparchus contains 1022 stars, with their positions for the year 128 before the vulgar era; which great work was happily preserved by Ptolemy.

Hipparchus, on comparing his observations on the Virgin's spike, with those of Timocharis, made a century before, was the first who discovered that the stars changed their positions, and appeared to advance slowly from west to east, in regard to the equinoctial point. This is called the precession of the equinoxes, by means of which the signs of the zodiac, or the points of the annual revolution of the Sun, make the circuit of the heavens and the constellations, in the space of 25,000 years.

Since the observations and theories of Hipparchus, we meet with nothing useful to the progress of astronomy, except the works of Ptolemy, an astronomer of Alexandria, who lived between the years 125 and 141 of the vulgar era. His Almagest is the only important work that is left us of ancient astronomy; and though his system and observations are but little esteemed, we are frequently obliged to have recourse to them. If, therefore, the theories on the motions of the planets, which his work contains, are his own, this author has rendered essential service to astronomy.

During the succeeding ages, the cultivation of this science was greatly neglected: it appears to have been confined to mere translations and comments upon the works of Ptolemy. We meet only with some Arabian observations made under the Caliph Almamoun, who reigned at Bagdad in the year 814; some few of Albategnius, an Arabian prince, who lived about the end of the same century; and of Ulug-Beg, grandson of the great Tamerlane, who reigned in Bactriana about the year 1437. This prince has left us a catalogue of stars, which is still much esteemed.

Astronomy made no very remarkable progress till the time of Copernicus, a native of Prussia Royal, born in 1472. From the year 1507, he began to consider the imperfection and complication of the hypothesis at that time admitted, to explain the motions of the planets; whence he perceived that they might be greatly simplified, by supposing that the Earth turned round the Sun. Fearing, however, to announce so extraordinary a principle, without affording positive demonstration, he determined to examine each planet individually, and to ascertain its motion, that he might be enabled to construct some more correct tables than those of Ptolemy. He then ascertained, beyond the possibility of doubt, that all irregularities were perfectly explained by his new system. In the year 1530, he concluded his celebrated work, De Revolutionibus Orbium Coelestium, but it was long before he ventured to present it to the world, and the work did not appear till the 24th of May, 1543, the very day on which Copernicus died.

It is to this author we are indebted for those luminous ideas, and intense labours, which have so materially changed the face of astronomy, and led to its further progress. But Tycho Brahe, the greatest astronomer known in those days, was the first who, by his exactness and the number of his observations, revived the study of this science. On these, all the theories, tables, and discoveries of Kepler were founded; and their names, added to those of Hipparchus and Copernicus, well deserve to be immortalised. Tycho, who studied at Copenhagen, was born on the 13th of December, 1546, in the province of Scania, in Denmark. He was of an illustrious family, still existing in Sweden, under the name of Brahe, and connected with that of Lowendal. Finding that the eclipse of the Sun, on the 21st of August, 1560, happened exactly as astronomers had foretold, he conceived, from that moment, the most ardent desire to be capable of making similar predictions.

Frederick the First, king of Denmark, gave him the island of Huen, situated in the Baltic Sea, opposite Copenhagen, where, from the year 1582 to 1597, he made an immense number of observations. He determined the positions of the stars, observed the refractions and inequalities in the Moon, and furnished Kepler with the means of discovering the laws of motion of the planets, and of constructing a set of entirely new tables.

But Kepler, by the admirable conclusions which he drew from these observations, acquired even more reputation than Tycho Brahe. Kepler was born in 1571, in the duchy of Wirtemberg. He discovered the laws of the celestial motions, and composed new tables of the motions of the planets, which were used by all astronomers, from the year 1626 to the end of the seventeenth century.

The invention of telescopes, in 1609, gave rise to fresh discoveries. Galileo, availing himself of it at Florence, to observe the planets, perceived that there were mountains in the Moon, spots in the Sun, and a ring which encircles Saturn; that Venus was often horned like the Moon, and that Jupiter was accompanied by four little planets, which are called the satellites of Jupiter.

Hevelius, a magistrate of Dantzig, born in 1611, made, between the year 1641 and 1685, an immense number of observations. He composed a new catalogue of the stars, and his work is still valuable to the astronomer: but it is now become so exceedingly scarce, that it is to be found only in very extensive libraries; the entire edition having been consumed, in a fire occasioned by the treachery of a servant.

The establishment of the Academy of Sciences, at Paris, which met for the first time on the 22nd of December, 1666, forms one of the most memorable epochs in the history of astronomy, as well as in that of the other sciences which it embraces. It is to the taste for literary societies, which had commenced in France long before that period, that we may trace the progress of the belles lettres, the sciences, and philosophy. Bacon, who died in 1626, speaks with rapture of these societies. There were some of this description established by Père Mersenne, in 1638. But it was the great Colbert who sought out and drew together the learned in every branch of the sciences, of whom he composed our celebrated Academy. Astronomy has there been brought to great perfection. Among the most important of their discoveries, we consider the satellites of Saturn, the propagation of light, the magnitude and figure of the Earth, the application of pendulums to clocks, that of telescopes to quadrants in 1668, and that of micrometers to telescopes. All the principal points of astronomy were there discussed and established. In these are comprised, the theory of the Sun and Moon, their inequalities, diameters, and parallaxes; refraction, the obliquity of the ecliptic, and the irregularities of the satellites of Jupiter.

Huygens, Picard, the celebrated Cassini, who was invited to Paris in 1669, and La Hire, bore a principal part in these discussions.

But we owe to John Flamstead, a celebrated astronomer, and Member of the Royal Society of London, established about the same time, the largest catalogue of stars that had ever been published, which appeared in 1712. And we are indebted to Halley, who succeeded him, among other things, for the first prediction of the return of a comet, which was verified fifty-four years afterwards; that is to say, in 1759.

All discoveries in astronomy were, however, eclipsed by those of Newton; who ascertained and published, in 1687, the fundamental law of the universe, or of universal attraction, by which all the phenomena of nature were explained: the motions of the planets, the inequalities of the Moon, the spheroidical figure of the Earth, the return of comets, the flux and reflux of the tides; and even the cause of the precession of the equinoxes, which was one of the most obscure and complicated of these phenomena.

But since Newton's time, every branch of astronomy has been brought to still greater perfection. The figure of the Earth, the inequalities of the Moon, of the planets, and the satellites of Jupiter, the small motions of the stars, the return of the comet in 1759, and the real distances of the planets from the Sun and the Earth, have been correctly ascertained; to which we may add, the discovery of five new planets, whose existence was not even suspected. All these subjects will be explained in the little volume which I now offer to my fair readers. May they be induced by its perusal, to seek, in a more extensive work, for a further knowledge of the sublime spectacle of the universe.

Last Updated December 2021