约翰·赫歇尔John Frederick William Herschel

约翰·赫歇尔是威廉·赫歇尔的儿子，后者是发现天王星的天文学家。他的母亲Mary Pitt是一位富商的女儿。她嫁给威廉·赫歇尔时38岁，她的第一任丈夫和唯一的孩子都已去世。1792年赫歇尔出生时，威廉·赫歇尔55岁，Mary 42岁。除了父母之外，他的姑母卡罗琳·赫歇尔也是赫歇尔成长过程中的另一位重要人物。

威廉·赫歇尔不仅是一位杰出的天文学家，还极具音乐天赋。他和他的妹妹卡罗琳·赫歇尔都极富音乐才能，初到英格兰后，两人都曾利用自己的音乐才能来增加收入。弗瑞兹·约翰在拥有40英尺望远镜的天文台宅邸中长大，那里音乐、科学和宗教占据主导地位。卡罗琳·赫歇尔在哥哥结婚后离开了他的家，但她仍每天来到天文台宅邸，帮助威廉·赫歇尔整理数据，并且她证明了自己是约翰的杰出老师，与这个小男孩一起进行物理和化学实验。

学校教育确实给约翰带来了一些问题。在希查姆的格雷顿博士学校学习后，他八岁时被送到伊顿公学，但遭到其他男孩的欺凌。几个月后，他的母亲将他从学校接走。除了在克莱沃和希查姆上学外，约翰还在家里由私人数学导师罗杰斯先生辅导，为上大学做准备。他于1809年进入剑桥大学圣约翰学院。

作为本科生，赫歇尔与乔治·皮科克和查尔斯·巴贝奇结为朋友。1812年，这三位本科生创立了分析学会，其目标是将欧洲大陆的数学分析方法引入英格兰的大学。这里可以公平地说，其目标是将欧洲大陆的数学理论引入英格兰的大学，因为当时苏格兰的大学更为进步。我们还应当说，分析学会并非英格兰走向欧洲大陆数学的第一步，因为罗伯特·伍德豪斯——他是赫歇尔在剑桥的讲师之一——曾写过一本好书，该书对微积分采取了哥特弗里德·威廉·莱布尼茨的进路，而非艾萨克·牛顿的进路。然而，剑桥的数学教学大纲没有反映让·勒朗·达朗贝尔、哥特弗里德·威廉·莱布尼茨的任何理论（特别是莱昂哈德·欧拉对这一进路的发展），也没有反映约瑟夫·拉格朗日更为代数化的进路。

赫歇尔与乔治·皮科克一起翻译了西尔维斯特·佛朗索瓦·拉克鲁瓦的Traité du calcul différentiel et du calcul intégralⓉ（《微分学与积分学专论》），该书考察了微积分的这些不同进路。赫歇尔并未以同等的推荐程度提出这三种进路，因为他认为约瑟夫·拉格朗日的代数进路才是正确的。然而分析学会并未存续很久。赫歇尔于1813年毕业，在毕业考试中名列第一。乔治·皮科克位居赫歇尔之后名列第二，而查尔斯·巴贝奇则已退出，主要是因为他无法与赫歇尔竞争，而且他不准备参加一场他自知无法获胜的竞争。

毕业后，赫歇尔成为第一位史密斯奖得主，并当选为圣约翰学院的研究员。同样在1813年，他当选为伦敦皇家学会的会士，此前已在Transactions of the Royal Society上发表了一篇数学论文On a remarkable application of Cotes's theorem。尽管分析学会解散，赫歇尔仍继续从事数学研究。他研究代数，并发表了关于三角级数的论文。在许多数学著作中，他于1820年出版了一本两卷本的书，内容是关于有限差分的应用实例。他的数学工作一直持续到1820年（他对数学的兴趣在许多后来关于其他主题的著作中也很明显），但甚至在1820年之前，他对其他学科的兴趣已经开始使他偏离数学研究。

有趣的是，从某些方面来说，正是由于赫歇尔非凡的全面才能，他才未能在所研究的任何学科中取得他显然有能力达到的深度进展。在所有学科中，他本可以成为我们今天所铭记的那个时代的世界领军人物。然而，他对如此多领域的贡献意味着，当他本可以在某一领域巩固自己的工作时，他通常已经转向了其他事情。当然，他的数学工作虽然重要，但从未产生过如果他继续在该领域工作本可能取得的影响力。

也许最令人惊讶的是赫歇尔毕业后的决定。他决定进入法律行业，这与他父亲的建议大相径庭，他父亲希望他加入教会，他于1814年2月前往伦敦开始培训。不久他就发现这并不适合他，并于1814年9月写信给查尔斯·巴贝奇说，既然这是他自己选择的职业，他会坚持下去。然而，18个月后，他放弃了法律培训，回到剑桥担任数学导师和考官。

1816年夏天，赫歇尔与父亲共度了一个假期。他似乎在这个假期中决定转向天文学，几乎可以肯定是因为他78岁的父亲健康状况正在恶化，且没有其他人能继续父亲的工作。他在1816年10月10日写信给查尔斯·巴贝奇（见C A Ronan在[6]中的文章）：-

我将于周一前往剑桥，打算只在那里停留足够的时间来结清账单、收拾书籍，并向大学作一次漫长的——也许是最后的告别。……我将在父亲的指导下，从他中断的地方继续他的一系列观测（因为他现在已经基本放弃了定期观测），并用强大的望远镜继续他对天空的审视……

赫歇尔从此时开始从事天文学工作，尽管他也研究其他课题。甚至在他的第一篇天文学论文发表之前，赫歇尔就在1819年发表了他的化学和摄影实验的细节，这些实验在20年后被证明对摄影的发展具有根本重要性。他积极参与了1820年天文学会的创立，并在该学会第二次会议上当选为副主席，当时学会的官员被选举出来。赫歇尔的多才多艺体现在，1821年，他最近刚涉足天文学和化学，就因在数学分析方面的工作而被授予伦敦皇家学会的科普利奖章。

查尔斯·巴贝奇和赫歇尔保持着亲密的朋友关系，两人于1821年一起前往意大利和瑞士旅行。他们都热爱登山，但他们在山上的活动不仅仅是为了消遣，因为赫歇尔不断从环境中学习科学知识。赫歇尔的其他出国旅行包括1822年的一次，以及1824年与查尔斯·巴贝奇的一次。这些旅行包括拜访其他科学家，例如在Paris Herschel和查尔斯·巴贝奇曾与弗朗索瓦·阿拉戈、皮埃尔·西蒙·拉普拉斯和让-巴蒂斯特·毕奥讨论共同感兴趣的话题。在1824年的旅行中，赫歇尔拜访了Fraunhofer，并会见了当时正在拜访Fraunhofer的威廉·亨利·福克斯·塔尔博特。他还拜访了约翰·弗里德里希·普法夫，后者正在从事他父亲著作的德文翻译工作，以及他的姑母卡罗琳·赫歇尔，她在1822年她的兄弟（赫歇尔的父亲）去世后回到了汉诺威。

事实上，1822年是赫歇尔发表第一篇天文学论文的年份，这是一篇相对次要的关于计算月食新方法的著作。他在天文学方面的第一部重要出版物是一份双星目录，于1824年发表在Transactions of the Royal Society上，并因此获得了荣誉。Paris Academy于1825年授予他拉朗德奖，Astronomical Society于次年授予他金质奖章。

关于双星的工作是作为他父亲工作的延续而进行的，他父亲试图测量一颗恒星的视差。视差是由于地球在绕太阳轨道上位置的变化，一颗相对较近的恒星相对于非常遥远的恒星背景所表现出的位置变化。赫歇尔在1826年发表了一篇关于这个主题的重要论文，但未能成功测定任何恒星的视差。他继续研究双星直到1833年，特别是他发展了确定那些围绕共同重心运行的双星轨道的方法，并因此项工作于1833年获得了皇家学会的皇家奖章。弗里德里希·威廉·贝塞尔是第一个证明恒星视差的人，于1840年发表了他的结果。

1830年，赫歇尔发表了他著名的论著Discourse on Natural Philosophy，其重要性在麦可·法拉第写给赫歇尔的信中得到了精彩的描述：-

……当你的自然哲学研究著作问世时，我和其他人一样欣喜地阅读了它。我把它当作哲学家的教科书，并感到它使我成为一个更好的推理者甚至实验者，并且全面提升了我的人格，使我——如果允许我这样说——成为一个更好的哲学家。

赫歇尔与皇家学会的交往对他的职业生涯产生了重要影响。他于1824年当选为该学会的秘书（尽管他在1827年辞职），并且在1831年，由查尔斯·巴贝奇提名竞选皇家学会的主席。这是学会内部改革派与守旧派之间斗争的一部分，赫歇尔是改革派的领袖。对赫歇尔来说，这是一段略显尴尬的经历，他仅以微弱劣势落选，守旧派获胜。他已于1827年当选为天文学会的主席，并于1831年被封为爵士，因此尽管对皇家学会感到失望，他仍获得了极大的认可。

此处一段未译出，以下为英文原文The Royal Society episode may have been the main reasons why Herschel decided to make a long visit to the Cape of Good Hope in South Africa. Also it became possible at this time because of the death of his mother Mary Herschel in 1832. The Royal Observatory had been completed at the Cape of Good Hope in 1828 with the scientific aim to catalogue interesting astronomical objects which could not be observed from the northern hemisphere. Herschel sailed for South Africa in 1833, taking with him his own 20 foot refractor telescope. He travelled with his family, having married Margaret Brodie Stewart four years earlier, and their ship reached South Africa in January 1834.

赫歇尔在南非取得的许多重要科学进展中，包括他对爱德蒙·哈雷彗星1835年回归的观测。他认识到这颗彗星受到了除引力之外的主要力的作用，并且能够计算出这个力是将其从太阳推开的力。这在某种意义上可以说构成了太阳风的发现，而太阳风确实是赫歇尔所发现的排斥力的原因。他还做出了一个重要发现，即气体正在从彗星中蒸发。

地质学家Lyell看到了其中的讽刺意味：赫歇尔之所以在南非做这项工作，是因为他未能当选皇家学会的主席。他写道（例如见[6]）：-

想想看，用开普敦的赫歇尔换赫歇尔担任皇家学会的主席，而他差一点就当上了，我还投了他的票！我希望为此得到原谅。

关于赫歇尔在南非期间的更多信息可在THIS LINK获取。

1838年，赫歇尔返回英国，没有多少时间整理他在那里所做的许多观测。他的意图是一返回就着手处理这些观测，但他被其他事务缠身，以至于这项任务直到1847年才完成。尽管有所延迟，该出版物仍是一件极其重要的事件，赫歇尔因此项工作从皇家学会获得了他的第二枚科普利奖章。他返回后妨碍他处理观测的事务部分是非科学性的，例如他在1838年6月接受了对准男爵爵位的投资，他相当不情愿地接受了。然而，主要的干扰是科学方面的。

1839年1月22日，赫歇尔从Beaufort写给他妻子Margaret的信中的一句随口之言听说了Daguerre在摄影方面的工作。在不知道任何细节的情况下，赫歇尔在几天内就能自己拍摄照片。威廉·亨利·福克斯·塔尔博特于2月1日拜访了他，讨论他们各自的摄影实验。在[6]的文章中，塞缪尔·罗伯茨引用了赫歇尔妻子的一封信：-

我碰巧清楚地记得威廉·亨利·福克斯·塔尔博特先生访问斯劳的情形，他来向赫歇尔展示他用新方法拍摄的精美的蕨类和小饰物小照片。——当有人谈到固定照片的困难时，赫歇尔说“让我把这张拿去几分钟”，过了一会儿他回来，把照片交给威廉·亨利·福克斯·塔尔博特先生，说“我想你会发现它已经固定了”——这就是硫代硫酸盐定影法的开端。

赫歇尔之所以能够取得这一异常迅速的突破，是由于他在1819年进行并发表的与摄影相关的化学过程方面的工作。赫歇尔随后在1839年、1840年和1842年又发表了许多关于摄影的论文。事实上，许多人一直感到奇怪，为什么赫歇尔本人从未迈出那些本会使他被公认为摄影术发明者的步骤。从他1819年的工作算起，有大约20年的时间他本可能取得突破，但这很可能又是由于他兴趣才能过于广泛，才未能做到。他的才能不仅把他带入广泛的其他活动，而且他作为艺术家的高超技艺意味着，他比大多数人都更不需要发明摄影术！

1850年，赫歇尔就自己职业生涯的未来方向做出了一个相当奇怪的决定。他曾拒绝作为剑桥大学议员进入议会，也拒绝了一项让他成为皇家学会主席的提议。他确实在1842年成为阿伯丁的马歇尔学院院长，并于1845年担任剑桥英国协会主席。然而在1850年，他接受了造币厂厂长的职位。因此，他在一个非常困难的时期成为造币厂的负责人，当时一项重大改革已经商定但尚未开始实施。这不是赫歇尔喜欢的工作。在与员工打交道方面有困难，在与财政部打交道方面有困难，但也许对赫歇尔来说最重要的是，他不再能够追求自己的科学兴趣。

赫歇尔天生是科学家，不是商人。在经历了艰难的岁月之后，他常常因工作要求而与家人分离，尽管他尽力把工作做好，最终还是辞职了。这一职位的压力损害了他的健康，摆脱这些问题对他一定是一种极大的解脱。他在63岁时基本上退居科林伍德。说他退休，当然必须加上一句限定：他一生从未担任过任何有薪的科学职位。他当然没有从科学工作中退休，而是摆脱了造币厂那份他领取相当薪水、却要求极高的职务之后，得以完成许多他和父亲已经着手却从未完成的任务。正如彼得·格思里·泰特所写（例如见[10]）：——

赫歇尔漫长而幸福的一生中，每一天都为他的科学贡献增添了自己的一份。

尽管他没有取得今天使他为人铭记的重大突破，但他同时代的许多人都认为他是当时首屈一指的科学家。让-巴蒂斯特·毕奥认为，当皮埃尔·西蒙·拉普拉斯于1827年去世时，他是皮埃尔·西蒙·拉普拉斯的当然继承人。讣告[13]中这样写道：——

赫歇尔英国科学界所遭受的损失，比自艾萨克·牛顿去世以来所遭受的任何损失都大，而且这一损失很可能无人能够弥补……

文章13接着说道，比他的研究价值更高的还有：-

……是他的教学和榜样在唤醒公众对科学的力量和美的认识，以及激励和引导公众追求科学方面所产生的影响。

John Herschel was the son of William Herschel, the astronomer who discovered Uranus. His mother Mary Pitt was the daughter of a wealthy merchant. She was 38 years old when she married William Herschel, her first husband and her only child having both died. When John Herschel was born in 1792 William was 55 years old and Mary was 42. In addition to his parents, his aunt Caroline Herschel was another important figure in John Herschel's upbringing.

William Herschel was not only a leading astronomer but he also had a great talent for music. Both he and his sister Caroline Herschel were extremely musical, and they had both used their musical talents to help augment their income after first arriving in England. John was brought up in Observatory House, with its 40 foot telescope, where music, science and religion were dominant. Caroline Herschel had left her brother's home when he married, but she continued to come to Observatory House every day to help William reduce his data and she proved an outstanding teacher to John, carrying out experiments in physics and chemistry with the young boy.

Schooling did present some problems for John. After studying at Dr Gretton's School in Hitcham, he was sent to Eton College when he was eight years old but he was bullied by the other boys. He was removed from the school by his mother after a few months. In addition to schooling at Clewer and Hitcham, John was tutored at home by Mr Rogers, a private mathematics tutor, to prepare him for university. He entered St John's College Cambridge in 1809.

As an undergraduate Herschel made friends with Peacock and Babbage. In 1812 the three undergraduates founded the Analytical Society which had as its aim the introduction of Continental methods of mathematical analysis into English universities. It is fair here to say that the aim was to bring Continental mathematical theory into English universities since the Scottish universities were at this time more progressive. We should also say that the Analytical Society was not the first move towards Continental mathematics in England, for Woodhouse who was one of Herschel's lecturers at Cambridge, had written a fine book which took the Leibniz approach to the calculus rather than Newton's approach. Yet the mathematical syllabus at Cambridge reflected none of the theories of d'Alembert, Leibniz (in particular Euler's development of this approach), or of the more algebraic approach of Lagrange.

Herschel, together with Peacock, translated Lacroix's Traité du calcul différentiel et du calcul intégral Ⓣ which examined these different approaches to the calculus. Herschel did not offer these three approaches with equal recommendation for he believed that the algebraic approach of Lagrange was the right one. However the Analytical Society did not survive for very long. Herschel graduated in 1813 taking first place in the final examination. Peacock came second to Herschel while Babbage had withdrawn mainly because he could not compete with Herschel and he was not prepared to enter a competition which he knew that he could not win.

Following his graduation Herschel became first Smith's prizeman and was elected a fellow of St John's College. Also in 1813 he was elected as a fellow of the Royal Society of London, having published a mathematics paper On a remarkable application of Cotes's theorem in the Transactions of the Royal Society. Despite the demise of the Analytical Society Herschel continued to work on mathematics. He studied algebras and published papers on trigonometrical series. Among many mathematical works he published a two volume book in 1820 on examples of applications of finite differences. His mathematical work continued up to 1820 (and his interest in mathematics was evident in many later works on other topics) but even before 1820 his interest in other subjects had begun to take him away from research in mathematics.

It is interesting to think that it was in some ways due to Herschel's remarkable all round abilities that he failed to make an advance of the depth that he was clearly capable of in any of the subjects that he studied. In all of them he could have been the person that we remember today as the world leader of his time. Yet the fact that he contributed to so many areas meant that he had usually moved on to something else when he might have been consolidating his work in a single area. Certainly his mathematical work, important as it was, never had the influence which he might have been able to have achieved had he continued to work in the area.

Perhaps most surprising of all was the decision that Herschel made after graduating. He decided to enter the legal profession, much against the advice of his father who wanted him to join the Church, and he went to London in February 1814 to begin training. It was not long before he found that it was not right for him and he wrote to Babbage in September 1814 saying that he would stick it out since it was his chosen career. However, after 18 months, he gave up his legal training and returned to Cambridge as a tutor and examiner in mathematics.

Herschel spent a holiday with his father during the summer of 1816. He seems to have decided during this holiday to turn to astronomy, almost certainly influenced by the fact that at 78 years of age his father's health was failing and there was nobody else to continue his father's work. He wrote on 10 October 1816 to Babbage (see C A Ronan's article in [6]):-

I shall go to Cambridge on Monday where I mean to stay just enough time to pay my bills, pack up my books and bid a long - perhaps a last farewell to the University. ... I am going under my father's directions, to take up the series of his observations where he has left them (for he has now pretty well given over regular observing) and continuing his scrutiny of the heavens with powerful telescopes ...

Indeed John Herschel began to undertake work in astronomy from this time although he also studied other topics. Even before his first astronomy paper was published, Herschel published details of his chemical and photography experiments in 1819 which, 20 years later, would prove of fundamental importance in the development of photography. He was very much involved with the founding of the Astronomical Society in 1820 and he was elected vice-president at the second meeting of the Society when the officers of the Society were elected. Herschel's great versatility is shown by the fact that in 1821, having recently become involved in astronomy and chemistry, he was awarded the Copley Medal of the Royal Society of London for his work on mathematical analysis.

Babbage and Herschel remained close friends and the two travelled together to Italy and Switzerland in 1821. They shared a love of climbing mountains but their exploits here were not simply for pleasure as Herschel continually learnt about science from his environment. Other trips abroad by Herschel included one in 1822 and another with Babbage in 1824. These trips included visits to other scientist, for example while in Paris Herschel and Babbage had discussed topics of common interest with Arago, Laplace and Biot. On the 1824 trip Herschel had visited Fraunhofer and had met with Fox Talbot who was visiting Fraunhofer at the time. He also visited Pfaff, who was working on a German translation of his father's work, and his aunt Caroline Herschel who had returned to Hanover after the death of her brother (John Herschel's father) in 1822.

In fact 1822 was the year in which John Herschel published his first paper on astronomy, a relatively minor work on a new method to calculate eclipses of the moon. His first major publication in astronomy was a catalogue of double stars which he published in the Transactions of the Royal Society in 1824 and for which he received honours. The Paris Academy awarded him its Lalande Prize in 1825 and the Astronomical Society awarded him its Gold Medal the following year.

The work on double stars had been undertaken as a continuation of his father's work which attempted to measure the parallax of a star. The parallax is the apparent change in position of a relatively nearby star against the background of very distant stars due to the change in position of the earth in its orbit around the sun. John Herschel published an important paper on this topic in 1826 but did not succeed in determining the parallax of any star. He continued to work on double stars until 1833, in particular he developed methods to determine the orbits of those double stars which orbited a common centre of gravity and for this work he received the Royal Medal of the Royal Society in 1833. Bessel was the first to demonstrate the parallax of a star, publishing his results in 1840.

In 1830 Herschel published his famous treatise Discourse on Natural Philosophy the importance of which is beautifully described by Faraday in writing to Herschel:-

... when your work on the study of Natural Philosophy came out, I read it, as others did with delight. I took it as a school book for philosophers, and feel that it has made me a better reasoner and even experimenter, and has altogether heightened my character, and made me, if I may be permitted to say so, a better philosopher.

Herschel's involvement with the Royal Society had important influences on his career. He had been elected Secretary of the Society in 1824 (although he resigned in 1827) and, in 1831, he was proposed by Babbage for President of the Royal Society. This was part of a battle that was going on in the Society between reformers and traditionalists, Herschel being the champion of the reformers. In a slightly embarrassing episode for Herschel, he failed narrowly to be elected, the traditionalists winning the day. He had been elected as President of the Astronomical Society in 1827 and he was knighted in 1831 so he received great recognition despite his disappointment with the Royal Society.

The Royal Society episode may have been the main reasons why Herschel decided to make a long visit to the Cape of Good Hope in South Africa. Also it became possible at this time because of the death of his mother Mary Herschel in 1832. The Royal Observatory had been completed at the Cape of Good Hope in 1828 with the scientific aim to catalogue interesting astronomical objects which could not be observed from the northern hemisphere. Herschel sailed for South Africa in 1833, taking with him his own 20 foot refractor telescope. He travelled with his family, having married Margaret Brodie Stewart four years earlier, and their ship reached South Africa in January 1834.

Among the many important scientific advances made by Herschel in South Africa was his observations of Halley's comet on its 1835 return. He recognised that the comet was being subjected to major forces other than gravitation and he was able to calculate that the force was one repelling it from the sun. This could in some sense be said to constitute the discovery of the solar wind which is indeed the reason for the repulsive force discovered by Herschel. He also made the important discovery that gas was evaporating from the comet.

The geologist Lyell saw the irony in the fact that Herschel had done this work in South Africa because he failed to be elected President of the Royal Society. He wrote (see for example [6]):-

Fancy exchanging Herschel at the Cape for Herschel as President of the Royal Society, which he so narrowly missed being, and I voted for him too! I hope to be forgiven for that.

More information on Herschel's time in South Africa is available at THIS LINK.

In 1838 Herschel returned to England not having had much time to reduce the many observations that he had made while there. His intention was to work on these as soon as he returned but he was kept so busy with other events that this task was not completed until 1847. Despite the delay, the publication was an event of great importance and Herschel received his second Copley Medal from the Royal Society for this work. The events which prevented him from working on his observations after his return were partly non-scientific such as his investment to a baronetcy in June 1838 which he accepted with considerable reluctance. The main distractions were, however, scientific ones.

On 22 January 1839 Herschel heard of Daguerre's work on photography from a casual remark in a letter written by Beaufort to Margaret his wife. Without knowing any details, Herschel was able to take photographs himself within a few days. Fox Talbot visited him on the 1 February to discuss their separate experiments in photography. In his article in [6] Roberts quotes from a letter by Herschel's wife:-

I happen to remember well the visit to Slough of Mr Fox Talbot, who came to show Herschel his beautiful little pictures of Ferns and Laces taken by his new process. - when something was said about the difficulty of fixing the pictures, Herschel said "Let me have this one for a few minutes" and after a short time he returned and gave the picture to Mr Fox Talbot saying "I think you'll find that fixed" - this was the beginning of the hyposulphite plan of fixing.

Indeed Herschel was able to achieve this remarkably rapid breakthrough due to the work that he had conducted and published in 1819 on chemical processes related to photography. Herschel went on to publish a number of further papers on photography, in 1839, 1840 and 1842. In fact many people have wondered why Herschel himself never made the steps which would have led to his being recognised as the inventor of photography. There was a period of around 20 years from the time of his 1819 work when he might have made the breakthrough but again it was probably due to his wide ranging talents that he failed to do so. Not only did his talents take him into a wide range of other activities but his great skill as an artist meant that he had less need to invent photography than most others!

In 1850 Herschel made a rather strange decision as to the future direction of his career. He had turned down entering parliament as a Cambridge University member and he had also turned down a proposal that he become president of the Royal Society. He did become rector of Marischal College in Aberdeen in 1842 and served as president of the British Association at Cambridge in 1845. In 1850, however, he accepted the post of Master of the Mint. He thus became head of the Mint at a very difficult time, with a major reform already agreed but its implementation not begun. It was not a job which Herschel found to his liking. There were difficulties in dealing with staff, difficulties in dealing with the Treasury, but perhaps most significantly of all to Herschel, he no longer could pursue his scientific interests.

Herschel was a scientist by nature, not a business man. After difficult years, frequently separated from his family by the demands of the job which he tried his best to do well, he resigned. His health had suffered through the stresses of the post and it must have come as a great relief to him to be free of the problems. He essentially retired to Collingwood at this stage in his career being 63 years of age. To say he retired needs of course to be qualified with the remark that throughout his life he never held any paid scientific post. He certainly did not retire from scientific work but, free of the huge demands of the job at the Mint for which he had received a fair salary, he was able to complete many tasks which he and his father had started but had never reached completion. As Tait wrote (see for example [10]):-

Every day of Herschel's long and happy life added its share to his scientific services.

Although he made no major breakthroughs for which he is remembered today he was considered by many of his contemporaries as the leading scientist of his day. Biot considered him the natural successor to Laplace when he died in 1827. In the obituary [13] it is remarked:-

In John Frederick William Herschel British science has sustained a loss greater than any which it has suffered since the death of Newton, and one not likely to be replaced...

The article [13] then goes on to say that of even higher value than his research:-

... was the influence of his teaching and example in wakening the public to the power and beauty of science, and stimulating and guiding its pursuit.