尼可拉·路易·拉卡伊Nicolas Louis de Lacaille

尼可拉·路易·拉卡伊或德拉卡耶是夏尔-拉卡伊（1679-1731）和芭布·勒布伊的儿子。大多数传记作者都同意他的生日是1713年3月15日，尽管有些资料将他的生日标记为12月14日，更接近12月29日，即他受洗的日期。拉卡伊有三个哥哥、五个姐姐（其中一个叫玛丽-芭布）和一个妹妹。除了三个成为修女的女孩和本传记的主人公拉卡伊外，其余人都早逝。这个家庭至少在两代人的时间里一直住在阿登地区的吕米尼。他们拥有库尔代普雷城堡，拉卡伊就是在那里长大的。

Charles-拉卡伊是一个受过教育的人，他从军队退役以追求他的机械和科学兴趣。他对力学特别感兴趣，并发明了几台机器。从幼年起就负责拉卡伊的学习，他将自己的热情传递给了他。虽然家庭起初富裕，但Charles-拉卡伊在开始经营一家造纸厂的项目时负债累累，该项目失败了。1725年，波旁公爵派他去南特领导一个殖民项目，他的运气再次耗尽，因为该项目被放弃了。他接下来被旺多姆公爵夫人任命为巴黎以西阿内的监护人和猎人。

拉卡伊去巴黎以西48公里的Collège de Mantes-sur-Seine（现Mantes-la-Jolie）学习，然后于1729年获得奖学金进入巴黎的Collège de Lisieux。在这所学院，他学习了两年修辞学和哲学。这些年很艰难，因为他的健康状况很差，他努力吃足够的食物来维持生命。当他十八岁时，父亲去世，拉卡伊从他那里继承了大量债务（他自愿承担，而他的姐妹们管理父亲的资产）。拉卡伊设法继续他的教育，得益于Duque 拉卡伊 Henri de Bourbon的财政帮助，他曾是他父亲的朋友。他继续在Collège de Navarre学习神学，于1732年入学，在这个阶段打算成为牧师。他的父亲曾希望他进入教会，他非常尊重父亲的遗愿。

在此期间，拉卡伊偶然看到了欧几里得的Elements。在此之前，他所接受的教育主要是文学方面的，但他设法在没有老师帮助的情况下自学了几何学。他对数学产生了兴趣，并开始自学天文学。三年来，他在这些新的科学兴趣和神学研究之间保持平衡。他最终决定完全专注于前者，但他没有忘记自己的宗教背景。他已成为一名执事，并先后在圣艾蒂安迪蒙教堂和马扎林学院的礼拜堂担任此职。

通过天文学，阿贝 拉卡伊 与当时巴黎天文台台长 雅克·卡西尼 成为朋友。卡西尼的影响帮助 拉卡伊 改进了他的天文观测。他还与卡西尼的儿子塞萨尔-弗朗索瓦（常被称为 塞萨尔-弗朗索瓦·卡西尼·图里）和侄子让-多米尼克·马拉尔迪成为朋友。1735 年，拉卡伊 与马拉尔迪一起勘测了从南特到巴约讷的法国海岸。拉卡伊 于 1736 年 5 月开始在巴黎天文台工作，并一直待到 1740 年 1 月。1739 年 7 月，拉卡伊 与马拉尔迪和 塞萨尔-弗朗索瓦·卡西尼·图里 一起开始测量法国子午线。他们的目标是修正 让-多米尼克·德·卡西尼（1690 年）和 让-费利克斯·皮卡德（1669-70 年）早先的测量结果。这次勘测耗时约三年，经常在该国危险地区的险恶条件下进行。结果于 1743 年以 La Méridienne de France vérifiée Ⓣ（《法国子午线验证》）为题，以 塞萨尔-弗朗索瓦·卡西尼·图里 的名义发表。然而，拉卡伊 完成了所有计算，却对他在前言中仅得到对其帮助的致谢感到不满。他写信给 詹姆斯·布拉德利，并寄去了他另一本书的副本：-

……我还印刷了我与 塞萨尔-弗朗索瓦·卡西尼·图里 一起进行的所有几何和天文操作的细节，以修正他父亲关于地球形状的著作。如果我没有对 塞萨尔-弗朗索瓦·卡西尼·图里 先生的行为感到如此震惊，我本会同时寄给您，他完全占有了这本书，而他几乎只做了署名和支付印刷费用：如果这本书在售，我会为您买一本，为我自己买一本；但据我所知，这本书尚未出版。我在这里告诉您的并不是抱怨 塞萨尔-弗朗索瓦·卡西尼·图里 先生，而只是告知您作者和这部作品的情况。当您看到它时，您就能确信我有幸告诉您的事情，并可以通过您认识的我们科学院的人了解此事。然而，如果您不向任何人透露是我本人告诉您这件事，我会很高兴。我冒昧对您如此自由，请求千万原谅。但也请您相信，没有人比我更愿意在这个国家提供您认为我能够提供的所有服务……

子午线的测量证实了艾萨克·牛顿关于地球是一个两极扁平的球体的想法，1735年和1736年派往秘鲁和拉普兰的探险队的结果也证实了这一点。Académie des Sciences认识到拉卡伊的价值，并于1741年5月3日选举他为助理天文学家，当时他只有28岁。1745年4月5日，他被选为副天文学家，接替Grandjean de Fouchy（后者被任命为终身秘书）。Ian Stewart Glass在[7]中写道：-

[拉卡伊]比同时代的任何其他天文学家都更清楚地看到了对恒星和行星进行精确测量对科学的价值。作为当时席卷知识界的“启蒙运动”时期的一位学者，他是法国最早的艾萨克·牛顿信徒之一，而艾萨克·牛顿的引力理论在近五十年里一直遭到敌视和怀疑。勒内·笛卡儿关于充满定义不清的介质的空间中流体涡旋的错误理论仍然占据主导地位。但对行星、卫星和彗星位置的日益精确的观测使人们清楚地认识到，它们的运动只能用牛顿的理论来解释。事实上，可以说拉卡伊和他在巴黎的同时代数学家们在天体力学和整个物理学的发展方面是艾萨克·牛顿的真正继承者。

1739年，他被任命为巴黎马扎林学院的数学讲席，接替皮埃尔·伐里农。在那里，他根据自己在数学（Leçons de Mathématiques Ⓣ（数学教程），1741年）、力学（Leçons de Mécanique Ⓣ（力学教程），1743年）、天文学（Leçons d'Astronomie géométrique et physique Ⓣ（几何与物理天文学教程），1746年）和光学（Leçons d'Optique Ⓣ（光学教程），1750年）方面的讲座出版了许多教科书。这些著作中有许多被多次再版，然后被翻译成各种语言，这证明了它们在教学上的重要性。Abbé 拉卡伊经常以半价将这些书卖给他的学生，对经济收益不感兴趣。拉卡伊将他的天文台搬到了马扎林学院，那里为他建造了一个新的天文台，到1742年他停止了访问巴黎天文台。

1748年，他收到了詹姆斯·布拉德利关于他发现章动现象的论文的副本。他在1748年8月22日的一封信中回复他：-

自从这一发现的传闻传开以来，也就是大约十年前，我一直在最焦急地等待您的论文。我很厌恶看到我们的几位天文学家为据称是他们自己做出这一发现的荣誉而争吵……；但这一发现以及运动所遵循的规则实际上应该归功于您……自从收到您的信后，我做了一个翻译，并向我们的科学院宣读了一个摘录，科学院很高兴能获得您作为其成员之一。

事实上，詹姆斯·布拉德利已于1748年7月被选入科学院。在收到詹姆斯·布拉德利的论文后，拉卡伊调整了自己所有的观测以考虑章动。然而，这并没有得到许多法国同事的赞同，他们因这一举动而对他提出了严厉批评。事实上，正如Curtis Wilson在[20]中指出的那样，他几乎没有得到法国同事的支持：-

1742年，拉卡伊提出了一个改进天文学基础、修订太阳理论和编制星表的计划，并邀请科学院的其他天文学家与他共同进行这项工作。受到卡西尼家族的冷遇，遭到P C Le Monnier和让·勒朗·达朗贝尔的敌视，他独自推进这个计划，其英雄气概超越了单纯的肉体忍耐的勇气。前往南半球的旅程需要被视为服务于这一总体目标。

此处一段未译出，以下为英文原文 Indeed, one of Abbé Lacaille's greatest astronomical achievements was the cataloguing of the southern stars. On 20 November 1750 he embarked on the vessel Le Glorieux, commanded by d'Après de Mennevillette, a friend of Lacaille's. He headed to the Cape of Good Hope on a scientific expedition organised by the Académie des Sciences, set up at Lacaille's request. He arrived on 19 April 1751, after a detour to Rio de Janeiro. His observations, published in 1763 in Coelum Australe Stelliferum Ⓣ, include 10,305 distinct stars, immediately superseding Halley's previous catalogue, which was much smaller and less accurate. He identified fourteen new constellations, which he named after scientific instruments: Telescopium, Microscopium, Apparatus Sculptoris, Fornax chemical, Horologium, Reticulus rhomboidalis, Pyxis nautica, Antlia pneumatica, Octanis, Circinus, Norma, and Mons Menae. He described these constellations in Table des Ascensions Droites et des Declinaisons Apparentes des Etoiles australes renfermées dans le tropique du Capricorne ... Ⓣ (1756). Lacaille narrated in detail his journey to the Cape in Journal historique de voyage au Cap de Bonne-Espérance par feu M l'abbé de La Caille ... Ⓣ which was published posthumously in 1776. Abbé Carlier edited this publication and added a description of Lacaille's life. Two hundred years later, R Raven-Hart translated this work into English and it was published as Travels at the Cape, 1751-53: an annotated translation of 'Journal historique du voyage fait au Cap de Bonne-Espérance ...' (1976).

1751年，他在好望角期间对月球进行了一些观测。后来，当这些观测与拉朗德同时在柏林进行的观测结合起来时，使天文学家能够确定月球视差。1752年，他测量了Klipfontein与开普敦之间的子午线弧长。他的结果略有异常，表明地球略呈梨形。Ian Glass写道[7]：-

在奴隶的帮助下，他使用从巴黎带来的测量杆铺设了一条长12605米的精确基线。这条基线被用来校准两个大三角形的基线，其顶点分别位于他在开普敦的天文台和现奥罗拉村附近。端点站点的纬度使用天顶仪测量。发现南纬33度处的地球半径与法国北纬45度处的地球半径相当，这意味着该行星略呈梨形。

George Everest爵士在1821年解释说，拉卡伊的错误是由于附近山脉，特别是桌山的引力吸引造成的。Thomas Mclear爵士后来在1838年至1847年间修订了这一测量，并能够确认误差并非由于拉卡伊的测量误差，因为他的基线和纬度非常准确。

拉卡伊于1754年6月28日回到巴黎，继续他的研究。他创建了一种计算彗星轨道的方法，研究了天文折射，并出版了星历表和对数表等。1757年，他出版了Astronomiae Fundamenta Ⓣ（基础天文学），这是一份包含400颗最亮恒星的星表，远优于任何前作。值得注意的是，拉卡伊并未商业销售Astronomiae Fundamenta Ⓣ（基础天文学），而是将副本分发给感兴趣的人，费用自理。1758年，他出版了一套首次考虑行星摄动的太阳表。1761年，他观测了金星凌日。由于马扎林学院天文台不适合观测，拉卡伊与其他天文学家一起前往Charenton附近的Carrières。他当选为圣彼得堡、柏林、斯德哥尔摩、伦敦、哥廷根和博洛尼亚科学院的成员。

我们在上面提到了拉卡伊与詹姆斯·布拉德利的通信，但他肯定不是唯一与拉卡伊通信的天文学家。在1757年至1761年间，他与托比亚斯·梅耶交换了十三封信[15]：-

讨论了四个主要课题：天文折射、1759年爱德蒙·哈雷彗星的回归、通过月球距离确定地球经度，以及1761年7月6日金星凌日。第一个课题占主导地位，结果证明是一个特别棘手的问题。两位天文学家对折射修正的预测存在分歧，导致他们展开激烈辩论，各自坚定地捍卫自己的观测仪器，同时怀疑对方的仪器。在这种情况下，托比亚斯·梅耶是对的；拉卡伊从未意识到他的六分仪的刻度，尽管经过仔细校验，是有缺陷的。

拉卡伊继续工作，直到1762年在马扎林学院因痛风致命发作去世，这无疑因过度工作而加重。他49岁，大部分观测结果尚未发表。直到Francis Baily编制了一份目录，由英国协会于1847年出版，拉卡伊的所有观测结果才为人所知。他葬于马扎林学院的礼拜堂。

Nicolas-Louis de Lacaille or de la Caille was the son of Charles-Louis de Lacaille (1679-1731) and Barbe Rebuy. Most biographers agree on his birthday being 15 March 1713, though some sources mark his birthday on 14 December, closer to 29 December, the date of his baptism. Lacaille had three older brothers, five older sisters (one named Marie-Barbe) and one younger sister. All died at a young age except three girls, who became nuns, and Lacaille, the subject of this biography. The family had been living in Rumigny, in the Ardennes, for at least two generations. They owned the castle of Cour-des-Prés, where Lacaille grew up.

Charles-Louis was an educated man who had retired from the military to pursue his mechanical and scientific interests. He was particularly interested in mechanics and had invented several machines. Being in charge of Lacaille's studies from a young age, he transmitted his passions to him. Although the family were well off at first, Charles-Louis ran up debts when he embarked on a project to run a paper mill, which failed. Sent to Nantes by the Duke of Bourbon in 1725 to head a colonial project, his luck again ran out for the project was abandoned. He was next appointed by the Duchess of Vendôme as a guardian and huntsman at Anet, west of Paris.

Nicolas-Louis Lacaille went to study at the Collège de Mantes-sur-Seine (now Mantes-la-Jolie), 48 km west of Paris, and then, in 1729, with a scholarship to the Parisian Collège de Lisieux. At this College he studied rhetoric and philosophy for two years. These years were difficult since his health was so poor that he struggled to eat enough to stay alive. When he was eighteen, his father died, and Lacaille inherited a large amount of debt from him (he willingly took it upon himself while his sisters managed their father's assets). Lacaille managed to continue his education thanks to the financial help of Duque Louis Henri de Bourbon, who had been a friend of his father's. He went on to study theology at the Collège de Navarre, entering in 1732, intending at this stage to become a priest. His father had wanted him to enter the Church and he greatly respected the memory of his father's wishes.

During this time, Lacaille came across a copy of Euclid's Elements. His education until that point had mainly been literary, but he managed to teach himself geometry without the help of a teacher. He gained an interest in mathematics and started studying astronomy on his own. For three years, he balanced these new scientific interests with his theological studies. He eventually decided to focus entirely on the former, but he did not forget his religious background. He had become a deacon, and acted as such first in Saint-Étienne-du-Mont and later in the chapel of Collège Mazarin.

Through astronomy, Abbé Lacaille became friends with Jacques Cassini, then director of the Paris Observatory. Cassini's influence helped Lacaille improve in his astronomical observations. He also befriended Cassini's son, César-François (often called Cassini de Thury), and nephew, Jean-Dominique Maraldi. In 1735, Lacaille surveyed the French coast from Nantes to Bayonne, along with Maraldi. Lacaille started working in the Paris Observatory in May 1736, and stayed there until January 1740. In July 1739, along with Maraldi and Cassini de Thury, Lacaille began measuring the French meridian. Their objective was to revise earlier measures by Dominique Cassini (1690) and Jean Picard (1669-70). The survey took around three years and was often carried out in treacherous conditions in dangerous parts of the country. The results were published in 1743 with the title La Méridienne de France vérifiée Ⓣ under Cassini de Thury's name. Lacaille, however, had made all the calculations and was not happy that all he received was an acknowledgement of his help in the Preface. He wrote to James Bradley, sending a copy of another of his books:-

... I have also had printed the details of all the geometrical and astronomical operations that I have made with Cassini de Thury, to amend the work of his father on the figure of the earth. I would have sent it at the same time if I had not been so shocked by the behaviour of M Cassini, who has taken complete possession of this book, to which he has hardly done more than put his name and pay the costs of printing: if it had been on sale I would have bought a copy for you and one for me; but this book is not yet published so far as I know. What I am telling you here is not to complain about M Cassini but only to inform you about the author and the work. When you have seen it you can assure yourself of what I have the honour to tell you and can inform yourself of it through those of our Academy whom you know. However, you would please me by not revealing to anybody that I have told you about it myself. I ask a thousand excuses for the liberty that I have dared to take with you. But also I beg you to believe that there is nobody more inclined than myself to render all the services in this country that you judge me capable of...

The measurements of the meridian confirmed Newton's idea that the Earth was a sphere flattened at the poles, as did the results from the expeditions sent to Peru and Lapland in 1735 and 1736. The Académie des Sciences recognised Lacaille's worth and elected him as an assistant astronomer on 3 May 1741, when he was only 28 years old. On 5 April 1745, he was elected associate astronomer, replacing Grandjean de Fouchy (who was appointed perpetual secretary). Ian Stewart Glass writes in [7]:-

More than any other astronomer of his time, [Lacaille] saw the value to science of making accurate measurements of the stars and planets. A savant at the time of the 'enlightenment', which was then sweeping the intellectual world, he was one of the first French apostles of Newton, whose theory of gravitation had been looked upon with hostility and scepticism for almost fifty years. Descartes" erroneous theory of fluid vortices in a space filled with an ill-defined medium still held sway. But increasingly precise observations of the positions of the planets, moons and comets were making it clear that their movements could only be interpreted in Newtonian terms. Indeed, it can be said that Lacaille and the mathematicians who were his contemporaries in Paris were the true successors of Newton when it came to the development of celestial mechanics and physics as a whole.

In 1739, he was appointed to the chair of mathematics at Collège Mazarin, in Paris, succeeding Pierre Varignon. There, he published many textbooks based on his lectures in mathematics (Leçons de Mathématiques Ⓣ, 1741), in mechanics (Leçons de Mécanique Ⓣ, 1743), in astronomy (Leçons d'Astronomie géométrique et physique Ⓣ, 1746) and in optics (Leçons d'Optique Ⓣ, 1750). It is a testament to their didactic importance that many of these works were republished several times and then translated into various languages. Abbé Lacaille would often sell these books to his students at half their prize, not interested in financial gain. Lacaille moved his observatory to Collège Mazarin, where a new one had been built for him, stopping his visits to the Paris Observatory by 1742.

In 1748 he received a copy of James Bradley's paper on his discovery of nutation. He replied to him in a letter dated 22 August 1748:-

It was the paper from you that I waited for with the most impatience since the rumour of this discovery spread, that is, since about ten years ago. I have been disgusted to see several of our astronomers quarrelling over the glory of supposedly themselves having made this discovery ...; but it and the rules obeyed by the movements should in fact have been ascribed to you ... Since I received your letter I have made a translation from which I read an extract to our academy, which is happy to have acquired you as one of its members.

Indeed Bradley had been elected to the Academy of Sciences in July 1748. After receiving Bradley's paper, Lacaille adjusted all his own observations to allow for nutation. This, however, did not find favour with many of his French colleagues who were highly critical of him over this action. In fact he had little support from his French colleagues as Curtis Wilson points out in [20]:-

In 1742 ... Lacaille proposed a project for improving the foundations of astronomy, revising solar theory, and forming a star catalogue, and he invited the other astronomers of the Academy to join him in this undertaking. Cold-shouldered by the Cassinis, treated with hostility by P C Le Monnier and Jean d'Alembert, he carried the project forward on his own, with a heroism that went beyond the mere courage of physical endurance. The journey to the Southern Hemisphere needs to be seen as in the service of this overarching aim.

Indeed, one of Abbé Lacaille's greatest astronomical achievements was the cataloguing of the southern stars. On 20 November 1750 he embarked on the vessel Le Glorieux, commanded by d'Après de Mennevillette, a friend of Lacaille's. He headed to the Cape of Good Hope on a scientific expedition organised by the Académie des Sciences, set up at Lacaille's request. He arrived on 19 April 1751, after a detour to Rio de Janeiro. His observations, published in 1763 in Coelum Australe Stelliferum Ⓣ, include 10,305 distinct stars, immediately superseding Halley's previous catalogue, which was much smaller and less accurate. He identified fourteen new constellations, which he named after scientific instruments: Telescopium, Microscopium, Apparatus Sculptoris, Fornax chemical, Horologium, Reticulus rhomboidalis, Pyxis nautica, Antlia pneumatica, Octanis, Circinus, Norma, and Mons Menae. He described these constellations in Table des Ascensions Droites et des Declinaisons Apparentes des Etoiles australes renfermées dans le tropique du Capricorne ... Ⓣ (1756). Lacaille narrated in detail his journey to the Cape in Journal historique de voyage au Cap de Bonne-Espérance par feu M l'abbé de La Caille ... Ⓣ which was published posthumously in 1776. Abbé Carlier edited this publication and added a description of Lacaille's life. Two hundred years later, R Raven-Hart translated this work into English and it was published as Travels at the Cape, 1751-53: an annotated translation of 'Journal historique du voyage fait au Cap de Bonne-Espérance ...' (1976).

In 1751, while in the Cape, he made some observations of the Moon. Later, when put together with the observations carried out by Jérôme Lalande in Berlin at the same time, they allowed the astronomer to determine the lunar parallax. In 1752, he performed a measure of the arc of the meridian between Klipfontein and Cape Town. His results were slightly anomalous, suggesting that the earth was slightly pear-shaped. Ian Glass writes [7]:-

Aided by slaves, he laid out a precise baseline of 12605 metres length employing measuring rods brought from Paris. This was used to calibrate the baseline of two large triangles with vertices at his observatory in Cape Town and near the present village of Aurora. The latitudes of the end stations were measured using a zenith sector. The radius of the earth at 33 degrees south was found to be comparable to that at 45 degrees north in France, implying that the planet was somewhat pear-shaped.

Sir George Everest explained in 1821 that Lacaille was in error due to the gravitational attraction of the nearby mountains, particularly Table Mountain. Sir Thomas Mclear later revised this measure between 1838 and 1847 and was able to confirm that the error was not due to measurement errors by Lacaille for his baseline and latitudes were remarkably accurate.

Abbé Lacaille came back to Paris on 28 June 1754 and continued his research. He created a method to calculate the orbits of comets, he studied astronomical refraction and he published ephemerides and logarithmic tables, among other things. In 1757, he published Astronomiae Fundamenta Ⓣ, a catalogue of the 400 brightest stars that was far superior to any of its predecessors. It is of note that Lacaille did not sell the Astronomiae Fundamenta Ⓣ commercially, but distributed copies to those interested, paying for the expenses himself. In 1758, he published a set of solar tables that took planetary perturbations into account for the first time. In 1761, he observed Venus's passage in front of the Sun. Since the Observatory at Collège Mazarin was not ideal for it, Lacaille went to Carrières, near Charenton, along other astronomers. He was elected a member of the Science Academies of St Petersburg, Berlin, Stockholm, London, Göttingen and Bologna.

We mentioned above Lacaille correspondence with Bradley but he was certainly not the only astronomer with whom Lacaille corresponded. Between 1757 and 1761 he exchanged thirteen letters with Tobias Mayer [15]:-

Four major topics are addressed : astronomical refraction, the return of Halley's comet in 1759, the determination of terrestrial longitudes by means of Lunar distances and Venus's passage across the Solar disc on the 6th of July 1761. The first topic dominants, turning out to be a particularly thorny issue. A disagreement concerning the corrections of refraction predicted by both astronomers leads them into a heated debate, in which each one defends stoutly his own observation instrument while casting suspicion on the instrument of the other. In this case Tobias Mayer was right; Lacaille never came to realise that the graduation of his sextant, although carefully verified, was defective.

Lacaille continued working until his death at Collège Mazarin in 1762 due to a fatal attack of the gout certainly made worse due to over-work. He was 49 years old and had not published most of his observations. It was not until Francis Baily produced a catalogue that was published by the British Association in 1847 that all of Lacaille's observations became known. He is buried in the chapel of the Collège Mazarin.