彼得·巴洛Peter Barlow

彼得·巴洛是自学成才的，但这种教育足够好，使他能够成功竞争成为伍利奇皇家军事学院的助理数学教师。他于1801年被任命担任该职位，并开始在Ladies Diary上发表数学文章，他作为数学权威的地位变得足够稳固，以至于一段时间后，他被邀请为百科全书撰写各种数学文章。

除了这些文章，巴洛还出版了几本重要著作，例如1811年他出版了An elementary investigation of the theory of numbers，三年后他出版了A new mathematical and philosophical dictionary。

他最被铭记的是两项重要贡献。1814年，除了上面描述的那本书之外，他还出版了第二本书，题为New mathematical tables。这些很快被称为Barlow's Tables，这部作品给出了从1到10 000所有数字的因子、平方、立方、平方根、倒数和双曲对数。这本书[2]：-

……被认为如此准确和有用，以至于自那以后它一直被定期重印。

在圣安德鲁斯大学的数学图书馆里，我们有好几本这些表格的破旧副本，它们必定被密集使用了多年。然而，今天它们只具有历史意义，因为计算器和计算机使它们完全过时了。

巴洛的第二项主要贡献使他的名字至今仍为业余天文学家所熟知。他发明了巴洛透镜，一种由两块玻璃之间的无色液体组成的望远镜透镜[1]：-

“巴洛透镜”是这种望远镜透镜的一种改型，是燧石玻璃与冕牌玻璃的负消色差组合。

在他一生中，巴洛最大的成就是当选为皇家学会会士，并因其磁学研究而获得该学会的科普利奖章[2]：-

1819年，巴洛开始研究船体中的铁导致船舶罗盘偏差的问题。由于他提出了将罗盘与一块形状合适的铁并置以校正偏差的方法，他被授予科普利奖章……

然而，这些并不是他仅有的贡献。1817年，他出版了Essay on the strength and stress of timber，其中包含他在伍利奇军事机构进行实验时收集的数据。他还从事桥梁设计工作，特别是1819年至1826年间与Thomas Telford合作设计梅奈海峡大桥。那是第一座重要的现代悬索桥。

威斯敏斯特桥于18世纪40年代不顾城市商人的反对而横跨伦敦泰晤士河建成，并于18世纪50年代由Charles Labelye重建。然而，当19世纪20年代有人提出拆除并替换这座旧桥时，巴洛被咨询以计算拆除该结构将如何影响泰晤士河的潮汐。在巴洛报告之后，新伦敦桥由老弗瑞兹·约翰 Rennie设计，并由其子小约翰 Rennie建造。

巴洛在英国铁路建设时期十分活跃。George Stephenson是英国第一个修建铁路的人。1825年，第一列火车从达灵顿开往斯托克顿，而利物浦至曼彻斯特的30英里线路于1830年通车。这两个项目均由Stephenson建造，他认为坡度应小于1%，曲线半径应非常宽，至少为一公里。巴洛被任命为铁路皇家专员，并在19世纪30年代和40年代进行了若干实验，以检验Stephenson提出的坡度和曲率半径限制是否正确。他还试图确定最有效的钢轨形状。

Peter Barlow was self-educated but this education was sufficiently good that he was able to compete successfully to became an assistant mathematics master at the Royal Military Academy at Woolwich. He was appointed to the post in 1801 and he began publishing mathematical articles in the Ladies Diary and he became sufficiently well established as a leading authority on mathematics that after a while he was asked to contribute various articles on mathematics for encyclopaedias.

In addition to these articles, Barlow also published several important books, for example in 1811 he published An elementary investigation of the theory of numbers and three years later he published A new mathematical and philosophical dictionary.

He is remembered most for two important contributions. In 1814 he produced a second book, in addition to the one described above, entitled New mathematical tables. These soon became known as Barlow's Tables and this work gives factors, squares, cubes, square roots, reciprocals and hyperbolic logarithms of all numbers from 1 to 10 000. The book [2]:-

... was considered so accurate and so useful that it has been regularly reprinted ever since.

In the mathematical library at the University of St Andrews we have several well worn copies of these tables which must have been used intensely for many years. Today, however, they are only of historical interest since they were made completely obsolete by calculators and computers.

Barlow's second major contribution makes his name still well known by amateur astronomers today. He invented the Barlow lens, a telescope lens consisting of a colourless liquid between two pieces of glass [1]:-

The "Barlow lens", a modification of this telescope lens, is a negative achromatic combination of flint glass and crown glass.

In his lifetime Barlow's greatest achievement was being elected to the Royal Society and receiving its Copley medal for his work on magnetism [2]:-

In 1819 Barlow began work on the problem of deviation in ship compasses caused by the presence of iron in the hull. For his method of correcting the deviation by juxtaposing the compass with a suitably shaped piece of iron, he was awarded the Copley Medal ...

These were not his only contributions, however. In 1817 he published Essay on the strength and stress of timber which contains data he collected while conducting experiments at the military establishments in Woolwich. He also worked on the design of bridges, in particular working from 1819 to 1826 with Thomas Telford on the design of the bridge over the Menai Strait. It was the first major modern suspension bridge.

Westminster Bridge was built across the Thames in London, despite opposition from city merchants, in the 1740s and rebuilt by Charles Labelye in the 1750s. However when there was a move to demolish and replace this old bridge in the 1820s, Barlow was consulted to compute how the tides on the Thames would be affected by the removal of this structure. After Barlow reported, New London Bridge was designed by John Rennie Sr and built by his son John Rennie Jr.

Barlow was active during the period of railway building in Britain. George Stephenson was the first to build railways in Britain. In 1825 the first train ran from Darlington to Stockton while the 30-mile line from Liverpool and Manchester was opened to traffic in 1830. Stephenson, who constructed both projects, believed that gradients should be less than 1 percent and that curves should have very wide radii of at least a kilometre. Barlow was appointed as royal commissioner for railways and in the 1830s and 1840s he conducted several experiments to see if the limitation on gradients and radius of curvature proposed by Stephenson was correct. He also tried to determine the most efficient shape for the rails.