拉朗德Jérôme Lalande

拉朗德的父亲是Pierre Le Français。一个显而易见的问题是，为什么拉朗德的父亲不叫拉朗德。让我们在本文开头就澄清这一点。事实上，在他生命的最初二十年里，拉朗德被称为拉朗德 Le Français，但此后他自称拉朗德 Le Français de la Lande。在法国大革命时期，贵族姓氏当然是要避免的，所以此时他把“le”和“la”作为后续名字的一部分，写作拉朗德 Lefrançais de 拉朗德。[想想这个时期有多少法国数学家的名字以Le...或La...开头，正是因为这个原因]。为简便起见，我们在本文中统一使用拉朗德这个名字。

回到拉朗德的父母，他的父亲Pierre在布雷斯地区布尔格经营一家邮局并做烟草生意，娶了Marie-Anne-Gabrielle Monchinet。他们只有一个孩子，所以在这个时期非常罕见地，拉朗德作为独生子长大。他在里昂的耶稣会学院学习，在这个阶段他几乎决定加入耶稣会。事实上是他的父母鼓励他继续学业，去巴黎学习法律，他照做了。有点讽刺的是，拉朗德后来以无神论者闻名，却曾如此接近成为耶稣会士。

正是他父母希望他学习法律的愿望阻止了拉朗德加入耶稣会，但更令人惊讶的是，也正是这个愿望使他成为天文学家。在攻读法律学位期间，他寄宿在巴黎的克吕尼府邸，天文学家Joseph-Nicolas Delisle的观测台就在那里。拉朗德对天文学着迷，尽管他继续学习法律，但他也参加了Delisle在皇家学院的天文学讲座以及Pierre Lemonnier的数学物理讲座。他不仅在讲座中学习这门学科的理论方面，还作为热情的观测者和Delisle的助手参与其中。尽管对天文学感兴趣，拉朗德还是完成了法律学业，并在1751年，年仅十九岁时，取得了资格并准备回到家乡布雷斯地区布尔格从事法律工作。然而，Lemonnier对这个年轻人另有打算。

此处一段未译出，以下为英文原文A project had been set up to measure the parallax of the moon and Mars and hence determine their distances. Several sites had been chosen from which to make simultaneous observations and Nicolas Lacaille was sent by the Académie des Sciences to make observations from the Cape of Good Hope while Lemonnier, who was responsible for the observations to be made in Berlin, asked Lalande to go in his place. As no suitable instrument was available in Berlin, Lemonnier lent him his own quadrant which was reported to be the best such instrument in France. The visit proved highly successful for Lalande who, despite his youth, was admitted to the Berlin Academy and was able to discuss science with Voltaire, Maupertuis and Euler. Lalande's observations were published in Acta eruditorum, and in publications of the Berlin Academy and the Paris Academy. After his return to France, Lalande was elected to the Académie des Sciences in Paris on 4 February 1753.

对如此年轻的人来说，这是一项伟大的成就，而对虚荣的拉朗德来说，这极其令人愉快。他总是追求名声，并且在年轻时就轻易获得了名声。然而，他整个职业生涯都建立在追求更多名声之上，他的每一个行动都是为了获得更多的赞誉和表扬。另一方面，当他确实输掉一场公开争论，或遭受攻击时，他并不怀恨在心，只是重新投身于争取更多认可的工作中。他说（例如见[1]）：-

我是侮辱的油布，是赞扬的海绵。

事实上，即使在争论中处于下风，他也喜欢成为众人瞩目的焦点，但在他的第一次公开争论中，他最终站在了获胜的一方。

为了计算月球视差，必须考虑到地球并非完美球体，而是在两极扁平这一事实。为此，当然必须知道地球与完美球体相差的确切程度，而拉朗德在这个问题上与Lemonnier意见不合。Paris Academy设立了一个委员会来解决争论，委员会裁定支持拉朗德。这当然不会让Lemonnier高兴，他与拉朗德之间的关系也恶化了。

拉朗德接下来承担的任务之一是协助亚历克西斯·克劳德·克莱罗计算爱德蒙·哈雷彗星更精确的轨道。爱德蒙·哈雷对其轨道所作的观测曾被用来预测其回归，基于的假设是彗星轨道不受太阳系中除太阳外任何天体的影响。根据这一假设，曾预测其回归日期为1758年末或1759年初。亚历克西斯·克劳德·克莱罗、让·勒朗·达朗贝尔和莱昂哈德·欧拉都研究过三体问题，而亚历克西斯·克劳德·克莱罗现在具备了计算彗星轨道摄动所需的数学知识。计算要求很高，由拉朗德与妮科尔-雷娜·勒波特夫人共同承担。许多关于这项工作的叙述忽略了勒波特夫人做出的巨大贡献，她日夜进行数学计算，但拉朗德总是热衷于承认女性做出的巨大科学贡献，我们在下文提到他与女数学家合作的其他项目。1757年9月，结果公布，表明爱德蒙·哈雷彗星将比先前预期早一年回归。到1757年12月，彗星被观测到，这是可用于三体问题的新数学技术的一次伟大胜利。拉朗德随后基于这些计算出版了爱德蒙·哈雷彗星表的修订版。

1759年，拉朗德被问及是否愿意接任天文年历Connaissance des temps Ⓣ（时间知识）的编辑职务。他从1760年到1776年担任编辑，但在法国大革命期间，他被要求再次接管编辑职责，他从1794年一直担任到1807年去世。在他担任编辑期间，拉朗德添加了精确的月球与恒星距离表，这些表在航海中很有价值。在他接任编辑的那一年，拉朗德获得了另一个有声望的职位，即接替他的老师Delisle担任Collège Royale的天文学教授。他于1762年就任该职位，并担任了46年。

金星凌日发生了两次，第一次在1761年，第二次在八年后。同样，从地球上不同地点对行星经过太阳前方的精确时间进行观测，将允许进行视差测量并计算地球到太阳的距离。这些事件足够重要，以至于组织了国际合作，从不同地点进行观测，而拉朗德在协调这个项目中发挥了作用。在这些凌日之间，1765-1766年间，他在意大利旅行。在那里他会见了教皇，并请求他将尼古拉·哥白尼和伽利略的著作从Index的禁书目录中移除。他在Voyage d'un français en Italie Ⓣ（《法国人在意大利的旅行》）（1769年）中发表了一篇记述，该书共八卷[1]：-

拉朗德详细描述了价格、有趣的游览地点以及其他游客感兴趣的信息。

他还访问了英格兰，特别是格林尼治天文台，并了解了哈里森钟表的细节，这些钟表在确定经度方面取得了成功。他也写了一篇关于这些旅行的记述，对历史学家来说读起来引人入胜，但从未出版。

除了精确的观测之外，拉朗德还以其著作闻名。有些著作是在高深的研究层面上写成的，而另一些则是通俗层面的，他在向非专业人士阐述思想方面取得了巨大成功。他撰写了许多主题的著作，不仅限于天文学，但他最著名的著作是一部天文学著作，Traité d'astronomie Ⓣ（《天文学论著》）。他于1764年首次分两卷出版该书，第二版分四卷于1771年至1781年间问世。第三版包含其学生让·巴蒂斯特·约瑟夫·德朗布尔的重要贡献，共三卷，于1792年出版。除了是一部出色的天文学教材之外，Traité d'astronomie Ⓣ（《天文学论著》）对于任何希望进行观测并简化自己计算的人来说都是一本实用手册，因为它包含了大量关于仪器、其使用方法以及如何计算的信息。

在1791年第三版出版之前，拉朗德获得了当选法兰西公学院院长的巨大荣誉。他作为院长的首批举措之一，就是允许女性进入所有班级。他还采取了其他前瞻性举措，例如停止为获奖者使用拉丁文引文。

这时拉朗德已经六十岁了，他在法国大革命期间的恐怖统治中毫发无损地活了下来，他把这归因于自己的无神论观点。他开始更公开地表达这些观点，也许最公开的场合是在1794年6月8日的第一个最高主宰节上。当时庆祝的是一种取代基督教的宗教，而拉朗德在其中发挥了主导作用。他发表了一篇演讲，这给了他一个表达无神论观点的平台，他也借此机会试图缓和当时笼罩法国的极端爱国主义（引自[2]）：-

现在是时候宣布这些重要且无可争辩的真理了，这些真理为所有人民、所有时代、地球每个角落所知晓：对祖国的爱、对美德的爱和理性的统治……对祖国的爱不是爱国者唯一的职责。我们不可能都在军队、国家、艺术和科学中为我们的民族服务，但我们都可以来帮助我们的兄弟……正是这样，慈善加上对祖国的爱，将使我们真正无愧于我们的革命、我们的胜利和整个宇宙的钦佩。

他的事业蒸蒸日上，1795年5月17日他被任命为巴黎天文台台长。他有一段时间一直在编制一份重要的星表，到1796年它包含了30,000颗恒星，到这时他实际上已经实现了最初的目标。然而他继续这项工作，到1797年他的星表列出了41,000颗恒星。当他在1801年出版Histoire céleste françaiseⓉ（法国天空史）时，其中包括了一份超过47,000颗恒星的星表。这些星表是在他家人的帮助下编制的，我们将在本文后面作一些评论。

我们对拉朗德职业生涯的描述接近尾声，但让我们停下来看看他性格的某些方面。首先，[2]中对他的外貌描述如下：-

他是个极其丑陋的人，并为此感到自豪。他那茄子形的头骨和像彗星尾巴一样拖在身后的一头蓬乱头发，使他成为肖像画家和漫画家最喜欢描绘的对象。他声称自己身高五英尺，但尽管他在计算恒星高度时精确无误，他似乎夸大了自己在地球上的高度。他爱女人，尤其是才华出众的女人，并在言行上提拔她们。

许多人嘲笑他的无神论观点，说这是他对上帝把他造得如此丑陋的报复[2]：-

……他那双膝外翻的腿和佝偻的腿，他弓起的背和小猴般的脑袋，他苍白干瘪的面容和布满皱纹的窄额头，以及那两道红眉毛下，他那空洞而泛绿的眼睛。

事实上，拉朗德的性格似乎包含许多矛盾。他在18世纪90年代后期[2]：-

……一个偏爱君主制的自由思想者，一个钦佩耶稣会的无神论者，一个向年轻女性示爱的女权主义者，一如既往地丑陋，也一如既往地虚荣。

他继续宣扬无神论观点，1799年开始寻找学者加入他的Dictionary of Atheists。在这项工作中，他说（引自[2]，另见[1]）：-

传播科学之光要靠学者，以便有朝一日他们能够约束那些使大地流血的可怕统治者；也就是说，那些战争贩子。既然宗教产生了这么多这样的人，我们也可以希望看到这一切终结。

人们可能会想象，持有这些观点的人会反对拿破仑，但他并没有这样做，相反，他欢迎拿破仑在1802年至1804年掌权。事实上，拿破仑在1799年乐于同意拉朗德将自己的名字加入Dictionary of Atheists。然而后来，拿破仑认定教会作为盟友比作为敌人更好，教皇来到巴黎参加他的皇帝登基典礼。拉朗德借此机会重新出版了他的Dictionary of Atheists，其中包含拿破仑的名字，这导致新皇帝要求法兰西学院谴责拉朗德。让·巴蒂斯特·约瑟夫·德朗布尔当时是法兰西学院的终身秘书，他努力让拉朗德屈从皇帝的要求，同时又不显得损害学院成员所享有的备受珍视的思想自由。拉朗德拒绝停止提出他的无神论观点。

我们前面承诺过要谈谈拉朗德的家人，他们在计算和制作表格方面发挥了重要作用。他从未结婚，但有一个私生女玛丽-让娜·德·拉朗德，他教她数学，以便她能帮助他的工作。他还培养了他的表弟Michel Lefrançais，他称其为侄子。Michel娶了他的私生女玛丽-让娜·德·拉朗德，拉朗德随后称她为侄女。玛丽-让娜·德·拉朗德和Michel成为拉朗德家族团队的重要成员，日夜工作在他的许多项目上。例如，拉朗德的Abrégé de navigation historique, théorétique, et practique, avec des tables horairesⓉ（《历史、理论和实践导航摘要及时间表》）（1793年）是导航表，包含了他女儿进行的大量计算。Michel Lefrançais在1790年代协助让·巴蒂斯特·约瑟夫·德朗布尔测量子午线，并在那个项目中发挥了重要作用。尽管如上所述，拉朗德从未结婚，但他与Louise-Elizabeth-Félicité du Piery同居。她是拉朗德在巴黎天文台进行的大规模月球天文学研究的首席研究员，她成为巴黎第一位教授天文学的女性。拉朗德对女性在天文学中贡献的重视，特别是作为数学家和计算者，体现在他于1785年首次出版、1795年和1806年有新版本的Astronomie des dames中。

除了我们在上文提到的他在组织科学方面的作用之外，我们还要指出，他是共济会的一名活跃成员，并在巴黎创立了九姐妹共济会会所，该会所向杰出的作家和科学家开放。大多数杰出的作家、科学家、艺术家和政治家都加入了，包括1778年加入的⟦N2⟧。更多细节见[3]。当法国大革命导致Académie des Sciences关闭时，拉朗德试图建立一个他称之为Réunion des Sciences的新组织来继续其职能。

拉朗德在职业生涯末期承担的一项重要任务是完成J.É. 蒙蒂克拉的四卷本Histoire des mathématiques Ⓣ（数学史）中剩余的两卷。第三卷涵盖18世纪纯数学、光学和力学，共832页；第四卷涵盖18世纪天文学、数学地理学和航海术，共688页。它们于1802年出版，当时拉朗德70岁。我们还应当提到，他也在1802年设立了拉朗德奖。该奖每年颁发给当年对天文学做出最重要贡献的人。

拿破仑坚持要求拉朗德停止公开支持无神论，但随着拉朗德生病，这已变得不必要。1806年末，他患上了胸部疾病，几乎可以肯定发展成了肺结核。去世前几天，他写道：-

我有时会自娱自乐地说，我认为自己拥有所有人类美德。我这句话被狠狠地拿来攻击我，好像我声称“拥有所有人类美德”。事实上，我说的是“我认为我拥有它们”，这是完全不同的事情。尽管如此，我或许不该这么说；但我的良心要求我这样做。

很难评估拉朗德的贡献，因为他的个性确实影响了他在世时别人对他的看法。然而，很明显，他对数学科学的发展做出了巨大贡献，尽管这不是通过科学创新实现的，他在这方面表现甚少。相反，他的重要性在于作为一名教师，特别是支持像让·巴蒂斯特·约瑟夫·德朗布尔和皮埃尔·梅尚这样的学生，通过他对科学的组织，通过他极其精确的观测，这些观测有助于提供证据支持艾萨克·牛顿的引力理论以及后来关于三体问题的结果，以及他成功普及天文学。

Jérôme Lalande's father was Pierre Le Français. There is the obvious question of why Lalande's father was not called Lalande. Let us clarify this right at the beginning of this article. In fact, for the first twenty years of his life Lalande was known as Jérôme Le Français, but after this he called himself Jérôme Le Français de la Lande. Aristocratic names were certainly to be avoided at the time of the French Revolution, so at this time he made the "le" and "la" part of the following names and wrote Jérôme Lefrançais de Lalande. [Think just how many French mathematicians of this period have names beginning with Le... or La... for just this reason]. For simplicity we shall use the name Lalande throughout this article.

Returning to Lalande's parents, his father Pierre, who ran a post office and traded in tobacco in Bourg-en-Bresse, had married Marie-Anne-Gabrielle Monchinet. They only had one child so, very unusually for this period, Jérôme grew up an only child. He studied at the Jesuit College in Lyon and at this stage he nearly decided to join the Jesuit Order. In fact it was his parents who encouraged him to continue his education by going to Paris to study law, which he did. It is somewhat ironical that Lalande, who would later become renowned as an atheist, should have come so close to becoming a Jesuit.

It was his parents wish that he study law that stopped Lalande joining the Jesuits, but more surprisingly it was also this wish which turned him into an astronomer. While studying for his law degree he lodged at the Hotel de Cluny in Paris and it was there that the astronomer Joseph-Nicolas Delisle had his observatory. Lalande was fascinated by astronomy and, although he continued to study law, he also attended Delisle's astronomy lectures at the Collège Royale as well as Pierre Lemonnier's lectures on mathematical physics. He not only studied the theoretical side of the subject in lectures but he also participated as an enthusiastic observer and assistant to Delisle. Despite his interest in astronomy, Lalande completed his law studies and in 1751, still only aged nineteen, he qualified and prepared to return to his home town of Bourg-en-Bresse to practise law. However Lemonnier had other plans for the young man.

A project had been set up to measure the parallax of the moon and Mars and hence determine their distances. Several sites had been chosen from which to make simultaneous observations and Nicolas Lacaille was sent by the Académie des Sciences to make observations from the Cape of Good Hope while Lemonnier, who was responsible for the observations to be made in Berlin, asked Lalande to go in his place. As no suitable instrument was available in Berlin, Lemonnier lent him his own quadrant which was reported to be the best such instrument in France. The visit proved highly successful for Lalande who, despite his youth, was admitted to the Berlin Academy and was able to discuss science with Voltaire, Maupertuis and Euler. Lalande's observations were published in Acta eruditorum, and in publications of the Berlin Academy and the Paris Academy. After his return to France, Lalande was elected to the Académie des Sciences in Paris on 4 February 1753.

This was a great achievement for so young a man and for the vain Lalande it was extremely pleasing. He always sought fame and he had readily achieved it at a young age. Yet he was someone whose whole career was based on seeking more fame and his every action was made in order to gain further plaudits and praise. On the other hand when he did lose a public argument, or suffered attacks, he held no grudges and merely set himself back to working towards further recognition. He said (see for example [1]):-

I am an oilskin for insults and a sponge for praise.

In fact he enjoyed being in the limelight even when on the losing end of an argument, but in his first public dispute he ended up on the winning side.

In order to compute the lunar parallax it was necessary to allow for the fact that the Earth is not a perfect sphere but is flattened at the poles. To do this it was, of course, necessary to know the precise amount by which the Earth differed from a perfect sphere and Lalande disagreed with Lemonnier on the issue. The Paris Academy set up a commission to settle the argument and it decided in favour of Lalande. This certainly did not please Lemonnier and relations between him and Lalande soured.

One of the next tasks that Lalande undertook was to assist Clairaut in calculating a more accurate orbit for Halley's comet. The observations of its orbit made by Halley had been used to predict its return based on the assumption that the comet's orbit was not affected by any bodies in the solar system except the sun. On this assumption a date of late 1758 or early 1759 had been predicted for its return. Clairaut, d'Alembert and Euler had all worked on the three-body problem and Clairaut now had the necessary mathematical knowledge to compute the perturbations in the orbit of the comet. The calculations were very demanding and were undertaken by Lalande together with Mme Lepaute. Many accounts of this work ignored the enormous contributions made by Mme Lepaute, who worked night and day on the mathematical calculations, but Lalande was always keen to acknowledge the large scientific contribution being made by women and we mention below other projects on which he collaborated with women mathematicians. In September 1757 the results were released which showed that Halley's comet would return a year earlier than previously expected. By December of 1757 the comet was sighted, a great triumph for the new mathematical techniques available for the three-body problem. Lalande went on to publish a corrected edition of the tables of Halley's Comet based on these computations.

In 1759 Lalande was asked if he would take over the editorship of the astronomical almanac Connaissance des temps Ⓣ. He was editor from 1760 until 1776 but during the French Revolution he was asked to take over the editorial duties again which he did from 1794 until his death in 1807. During his editorship, Lalande added accurate tables of lunar distances from stars which were valuable in navigation. In the year he took over as editor, Lalande was offered another prestigious position namely to follow his teacher Delisle as professor of astronomy at the Collège Royale. He took up the post in 1762 and held it for 46 years.

Two transits of Venus occurred, the first in 1761 and the second eight years later. Again observations taken from different places on the Earth of the precise timing of the passage of the planet in front of the sun would allow parallax measurements to be made and the distance from the Earth to the sun to be calculated. These events were of sufficient importance to have international cooperation organised to have the observations made from different sites, and Lalande played a role in coordinating this project. Between these transits, during 1765-1766, he travelled in Italy. There he met the Pope and petitioned him to remove the writings of Copernicus and Galileo from the Index of prohibited works. He published an account in Voyage d'un français en Italie Ⓣ (1769) which ran to eight volumes [1]:-

Lalande went into great detail about prices, interesting places to visit, and other information of interest to the tourist.

He also visited England, in particular the Greenwich Observatory, and found out details of Harrison's clocks which had been successful in determining longitude. He wrote an account of these travels too which is fascinating for historians to read but was never published.

As well as his accurate observations, Lalande was also famous for his books. Some were written at a high-powered research level, while others were at a popular level where he had great success in presenting ideas to non-experts. He wrote on many topics, not just astronomy, but his most famous text was an astronomy one, Traité d'astronomie Ⓣ. He first published it in two volumes in 1764, with a second edition in four volumes appearing between 1771 and 1781. A third edition, containing important contributions by his student Delambre, consisting of three volumes was published in 1792. As well as being an excellent astronomy text, Traité d'astronomie Ⓣ was a practical manual for anyone wishing to observe and reduce their own calculations since it contained much information on instruments, their use, and how to compute.

Before the publication of the third edition, in 1791, Lalande achieved the great honour of being elected Head of the Collège de France. One of his first acts as Head was to admit women to all classes. He made other forward looking moves too, such as stopping Latin citations for prize winners.

By this time Lalande was sixty years old, he had survived the Terror during the French Revolution unscathed, something which he put down to his atheist views. He began to express these views more openly, perhaps the most public arena being on 8 June 1794 at the first Festival of the Supreme Being. What was being celebrated was a religion to substitute for Christianity and Lalande played a leading role. He gave a speech which allowed him a platform to express his atheist views and he also took the opportunity to try to moderate the extreme form of patriotism which was gripping France (quoted in [2]):-

The time has come to declare these important and incontestable truths, known to all people, at all times, and in every corner of the globe: love of country, love of virtue and the reign of reason ... . Love of country is not a patriot's only duty. We cannot all serve our nation in the army, in the state, in the arts and sciences, but we can all come to the aid of our brothers ... . It is this way that charity, added to love of country, will make us truly worthy of our revolution, our victories, and the admiration of the entire Universe.

His career went from strength to strength and on 17 May 1795 he was appointed director of the Paris Observatory. He had for some time been creating a major star catalogue and by 1796 it contained 30,000 stars and by this stage had, in fact, achieved his original aim. However he continued with the task and by 1797 his star catalogue listed 41,000 stars. When he published Histoire céleste française Ⓣ in 1801 it including a catalogue of over 47,000 stars. These star catalogues were constructed with the help of his family, and we will make some comments about them later in this article.

We are nearing the end of our description of Lalande's career, but let us pause to look at some aspects of his character. First his appearance is described in [2] as follows:-

He was an extremely ugly man, and proud of it. His aubergine-shaped skull and shock of straggly hair trailing behind him like a comet's tail made him the favourite of portraitists and caricaturists. He claimed to stand five feet tall, but precise as he was at calculating the heights of stars he seems to have exaggerated his own altitude on earth. He loved women, especially brilliant women, and promoted them in word and deed.

Many laughed at his atheist views saying that they were his revenge against God who had made him so ugly [2]:-

... his knock knees and rickety legs, his hunched back and little monkey's head, his pale wizened features and narrow creased forehead, and under those red eyebrows, his empty grassy eyes.

In fact Lalande character seemed to contain many contradictions. He was in the late 1790s [2]:-

... a free-thinker who preferred monarchy, an atheist who admired the Jesuits, a feminist who propositioned young women, as ugly as ever and still just as vain.

Continuing to promote atheist views, in 1799 he began to look for scholars to add to his Dictionary of Atheists. In this work he said (quoted in [2], see also [1]):-

It is up to the scholars to spread the light of science, so that one day they may curb those monstrous rulers who bloody the earth; that is to say, the warmongers. As religion has produced so many of them, we may hope to see an end to that as well.

One might imagine that someone with these views would have opposed Napoleon, but he did not do so and on the contrary he welcomed Napoleon's rise to power 1802 -1804. In fact Napoleon had been happy to agree that Lalande add his name to the Dictionary of Atheists in 1799. Later, however, Napoleon decided that the Church would make a better ally than enemy and the Pope came to Paris for his installation as Emperor. Lalande took the opportunity to reissue his Dictionary of Atheists with Napoleon's name included which caused the new Emperor to demand that the Institut de France censure Lalande. Delambre, who was at this time the Permanent Secretary to the Institut, tried hard to make Lalande bend to the Emperor's demands without being seen to undermine the highly prized intellectual freedom that members of the Institut enjoyed. Lalande refused to stop putting forward his atheist views.

We promised earlier to say something of Lalande's family who played a large role in computing and producing tables. He never married but he had an illegitimate daughter Marie-Jeanne-Amélie Harlay whom he trained in mathematics so that she could help him with his work. He also trained his cousin Michel Lefrançais whom he called his nephew. Michel married his illegitimate daughter Amélie whom Lalande then called his niece. Amélie and Michel became important members of the Lalande family team working day and night on many of his projects. For example Lalande's Abrégé de navigation historique, théorétique, et practique, avec des tables horaires Ⓣ (1793) were navigation tables containing a wealth of calculations carried out by his daughter. Michel Lefrançais assisted Delambre in his measurements of the meridian in the 1790s and played an important role in that project. Although, as we remarked above, Lalande never married he lived with Louise-Elizabeth-Félicité du Piery. She was the chief investigator on Lalande's large-scale study of lunar astronomy, which was undertaken at the Paris Observatory, and she became the first woman in Paris to teach astronomy. The importance in which Lalande held women's contributions to astronomy, particularly as mathematicians and calculators, is seen in his Astronomie des dames first published in 1785, with new editions in 1795 and 1806.

In addition to his role in organising science that we have mentioned above, let us also note that he was an active member of the Masonic order and that he founded the Masonic Lodge of the Nine Sisters in Paris which was open to leading writers and scientists. Most of the leading authors, scientists, artists and politicians joined including Voltaire in 1778. See [3] for more details. When the French Revolution led to the closure of the Académie des Sciences, Lalande attempted to set up a new organisation which he called Réunion des Sciences to carry on its functions.

One important task Lalande undertook near the end of his career was to complete the remaining two volumes of Montucla's four volume Histoire des mathématiques Ⓣ. Volume three covered 18th century pure mathematics, optics and mechanics in 832 pages, while the fourth volume covered 18th century astronomy, mathematical geography and navigation in 688 pages. They were published in 1802 when Lalande was 70 years old. We should also mention that he instituted the Lalande Prize, also in the year 1802. It was to be awarded annually for the most important contribution to astronomy made in that year.

Napoleon's insistence that Lalande stop his public support of atheism became unnecessary since Lalande fell ill. Towards the end of 1806 he contracted a chest complaint which almost certainly developed into tuberculosis. A few days before his death he wrote:-

I have sometimes amused myself by saying that I thought I possessed all the human virtues. This phrase of mine has been bitterly cast up against me as if I had claimed "to have all the human virtues". In fact, what I said was that "I thought I had them", which is quite a different matter. Nevertheless, I was perhaps wrong to have said as much; but my conscience required it of me.

It is hard to assess Lalande's contributions for his personality certainly affected the way he was viewed in his own lifetime. It is clear, however, that he made enormous contributions to the development of the mathematical sciences although this was not through scientific innovation of which he displayed little. Rather his importance lies as a teacher, particularly in supporting his students like Delambre and Méchain, through his organisation of science, by his superbly accurate observations which helped to provide evidence to support Newton's theory of gravitation and later results on the 3-body problem, and his successful popularising astronomy.