哈罗德·杰弗里斯Harold Jeffreys

哈罗德·杰弗里斯的父亲是罗伯特·H·杰弗里斯（约1867年出生于诺森伯兰郡费尔顿），他是一所中学的校长。他的母亲是伊丽莎白·M·A·杰弗里斯（约1864年出生于诺森伯兰郡斯坦宁顿）。他的父母于1890年结婚。

杰弗里斯·杰弗里斯先在法特菲尔德上学，然后于1903年获得奖学金，进入纽卡斯尔泰恩河畔的卢瑟福学院。1907年，他去了同样位于纽卡斯尔的阿姆斯特朗学院，该学院后来成为纽卡斯尔大学。当杰弗里斯进入该学院时，它是杜伦大学的一部分。在那里，他学习数学、物理、化学和地质学，1910年毕业，数学成绩优异。

离开纽卡斯尔后，他去了剑桥的圣弗瑞兹·约翰学院，获得了四项数学奖学金之一。在剑桥，对他产生强烈影响的老师包括亨利·弗雷德里克·贝克、布罗米奇、R·韦布、A·贝里和埃比尼泽·坎宁安。他于1914年成为剑桥圣约翰学院的会士，并终身担任会士。

杰弗里斯从1915年到1917年在卡文迪什实验室从事与战争相关的工作。他从1917年到1922年加入气象局，从事流体动力学问题的工作。他回到剑桥，并在那里教授数学直到1932年。杰弗里斯将继续留在剑桥的教职员工中，但不是作为数学家。从1932年到1946年，他在那里教授地球物理学，然后成为普卢米安天文学教授。

作为一名讲师，杰弗里斯名声不佳。以前的学生D J Finney回忆道：-

1937-8年，.. Lawley和我是剑桥的两名年轻数学研究生...我们开始时参加了杰弗里斯教授讲授的“Probability”课程。他并不是最清晰的讲师，我们很快就非常困惑...。杰弗里斯的个人魅力和热情并没有阻止出勤率的持续下降，直到Lawley和我发现自己是最初15人中仅存的两人。...有一周我们两人都无法参加，而接下来的一周我们尴尬地发现讲师已经放弃了这门课程。

杰弗里斯在多个科学领域的工作都以数学应用为纽带。在地球物理学中，他研究了地震和大气环流。由于对地震波的研究，杰弗里斯成为第一个声称地球核心是液态的人。

在天文学中，他研究外行星，提出其结构的模型。他还研究了太阳系的起源。

他获得了皇家天文学会（1937年）、Royal Society of London（1948年）的荣誉，并于1953年被授予爵士称号。1948年伦敦皇家学会授予他的是皇家奖章，授奖理由为：-

……表彰其在地球物理学中的杰出工作以及对太阳系天文学的重要贡献。

Royal Society于1960年授予他科普利奖章：-

……以表彰他在多个地球物理学分支中的杰出工作，以及在概率论和天文学方面的贡献。

杰弗里斯的著作有The Earth: Its Origin, History and Physical Constitution（1924年）、Earthquakes and Mountains（1935年），他还与妻子贝尔塔·斯韦尔斯合著了Methods of Mathematical Physics（1946年）。他们在序言中明确说明其目标是

阐述纯数学中物理学最常需要的那些部分。

在纯数学方面，他研究了运算方法（其中他改进了奥利弗·赫维赛德的运算微积分和拉普拉斯变换）、笛卡儿张量和渐近逼近。除Methods of Mathematical Physics外，他对纯数学的其他贡献收录于Theory of Probability（1939年）。他在概率论方面的工作沿贝叶斯路线发展，同样旨在应用于物理科学。

杰弗里斯的性格在[3]中有很好的体现，以下引文给出了一幅图景：-

多年来他吸烟很凶，在剑桥他到处骑自行车，直到90多岁，甚至在他因事故摔断手腕之后仍然如此。……尽管不爱交谈，杰弗里斯可以是个很好的谈话者……虽然害羞，[他]内心是个好社交的人……

杰弗里斯的一生在[3]中总结如下：-

杰弗里斯在许多国家受到尊重，甚至崇敬，但在那些熟悉他的人中，他所激起的不仅仅是尊重或崇敬，而是爱戴，对一个尽管作为数学家具有令人印象深刻的能力、尽管拥有广博而深厚的知识、尽管为发展地球物理学做了那么多，但内心却非常友好、谦逊、毫无骄傲或自负之人的爱戴。

Harold Jeffreys' father was Robert H Jeffreys (born at Felton, Northumberland about 1867) who was the headmaster of a secondary school. His mother was Elizabeth M A Jeffreys (born at Stannington, Northumberland, about 1864). His parents married in 1890.

Harold Jeffries attended school at Fatfield then, in 1903, he was awarded a scholarship to attend Rutherford College in Newcastle- upon- Tyne. In 1907 he went to Armstrong College, also in Newcastle, which later became Newcastle University. At the time Jeffreys entered the College it was a part of Durham University. There he studied mathematics, physics, chemistry and geology, graduating in 1910 with distinction in mathematics.

He went to St John's College, Cambridge after leaving Newcastle, having obtained one of four mathematics scholarships. Among his teachers at Cambridge to exert a strong influence on him were H F Baker, T J I'A Bromwich, R Webb, A Berry and E Cunningham. He became a fellow of St John's College, Cambridge in 1914 and remained a fellow all his life.

Jeffreys worked in the Cavendish Laboratories on war related work from 1915 until 1917. He joined the Meteorological Office from 1917 to 1922 where he worked on hydrodynamical problems. He returned to Cambridge and he lectured there in mathematics until 1932. Jeffreys was to remain on the staff at Cambridge, but not as a mathematician. From 1932 to 1946 he taught geophysics there, then he became Plumian Professor of Astronomy.

As a lecturer Jeffreys had a poor reputation. A former student D J Finney recalls:-

In 1937-8 .. Lawley and I were two young graduate mathematicians in Cambridge ... We began by attending a lecture course given by Professor Harold Jeffreys on 'Probability'. He was not the clearest of lecturers, and we were soon very confused ... . Jeffreys's personal charm and enthusiasm did not prevent a steady decline in attendance until Lawley and I found ourselves the only survivors of an initial 15. ... There came a week when we were both prevented from attending, and the following week we found to our embarrassment that the lecturer had abandoned the course.

Jeffreys's work in diverse areas of science had mathematical applications as their link. In geophysics he studied earthquakes, and the circulation of the atmosphere. As a result of his study of earthquake waves, Jeffreys became the first to claim that the core of the Earth is liquid.

In astronomy he studied the outer planets proposing models for their structures. He also studied the origin of the solar system.

He was awarded honours from the Royal Astronomical Society (1937), from the Royal Society of London (1948) and was knighted in 1953. The 1948 award from the Royal Society of London was their Royal Medal which they awarded:-

... for distinguished work in geophysics and his important contributions to the astronomy of the solar system.

The Royal Society awarded him their Copley Medal in 1960:-

... in recognition of his distinguished work in many branches of geophysics, and also in the theory of probability and astronomy.

Among Jeffreys's works are The Earth: Its Origin, History and Physical Constitution (1924), Earthquakes and Mountains (1935) and he wrote Methods of Mathematical Physics (1946) jointly with his wife Bertha Jeffreys. They state clearly in the preface that their aims are

to provide an account of those parts of pure mathematics that are most frequently needed in physics.

In pure mathematics he studied operational methods (where he improved on Heaviside's operational calculus and Laplace transforms), cartesian tensors and asymptotic approximations. In addition to Methods of Mathematical Physics other contributions of his to pure mathematics are contained in Theory of Probability (1939). His work in probability is developed along Bayesian lines and again aimed at application in the physical sciences.

Jeffreys's character is well illustrated in [3] and the following quotes give a picture:-

For many years he smoked intensely and in Cambridge he bicycled everywhere until over 90, even after he had broken his wrist in an accident. ... Although uncommunicative, Harold could be a good talker ... though shy, [he] was at heart a sociable man ...

Jeffreys's life is summed up in [3] as follows:-

Harold was held in respect, indeed reverence, in many countries, but in those who knew him well it was more than respect or reverence that he inspired, it was affection, affection for a man who for all his impressive abilities as a mathematician, for all his wide and deep knowledge, for all he had done to develop geophysics, was at heart a very friendly, unassuming person, quite free of pride or pretension.