Benjamin Wardhaugh - Gunpowder and Geometry

Hutton would later write that an advantage of the mathematical correspondence promoted by The Ladies’ Diary and its sisters was that ‘considerable additions are made to the stock of mathematical learning in general, as well as to the particular knowledge of individuals’. Behind the scenes, he was finding other ways to add to his own stock of mathematical learning. Having already attended the schools of Hugh James in Newcastle and Mr Robson at Delaval, once in Newcastle he embarked on a systematic, historically motivated programme of mathematical reading, covering the Greeks, Romans, Spaniards, French and Germans as well as British mathematical writers.

During 1763 he distilled the fruit of his reading and his teaching experience – all six years of it – into a short textbook on arithmetic. The School-master’s Guide was published in Newcastle on 3 March 1764.

Its subject was just what Hutton had been teaching: elementary arithmetic, beginning with addition, subtraction, multiplication and division. The book continued with proportional reasoning in all its diversity and how to find square roots and cube roots. There was little more: one of the selling points of the book was its spare, uncluttered approach. Yet the careful control with which Hutton increased the complexity of his examples, and his penchant for introducing new tricks, rules or exceptions midway through what looked like routine series of examples, certainly kept things interesting. We gain a sense of what Hutton’s teaching was like in person: agile, thoughtful, tremendously well organised. Whatever exercise is being done, there’s always a slightly harder version of it just over the page.

Indeed, one of the reasons for the Guide ’s success was the clarity with which it presented Hutton himself as a safe, sure, capable guide to the tricky territory of beginners’ arithmetic. Here was a man who loved calculation, who was almost preternaturally good at it. A man for whom common sense would unproblematically tell whether an answer was reasonable or not, for whom number sense was – as a matter of course – good enough to use obvious simplifications when the numbers in a calculation suggested them. For whom long division could be done largely in your head after a bit of practice: ‘when you are pretty ready in division, you may, even in the largest divisions, subtract each figure of the product as you produce it, and only write down the remainders.’

There were a few missteps in the Guide , indeed, when things were evidently clear to Hutton but he was unsuccessful in setting them out lucidly in words. Some of his attempts to give verbal equivalents of algebraic rules would have been scarcely comprehensible without the help of an able teacher. Some of his special tricks complicated more than they simplified: if a multiplier is itself a product, multiply by its factors separately. If it’s not a product, find a nearby number, multiply that, and then correct the answer by adding or subtracting.

But ultimately the aim of all his rules, tricks and practice examples was to impart to students something of his own feel for numbers, to help them develop a number sense and be able to select the right calculatory process even in an unfamiliar situation. And in that he appears to have succeeded.

Hutton moreover took pains to come across as a humane man, one who knew that children would get things wrong, that ‘calculations of the same accounts made at different times will sometimes differ’, that some pupils were simply not fitted for difficult calculation or found it off-putting. He drew on a wide range of personal knowledge to help the mathematics mean something to his students. Examples adopted almost every imaginable viewpoint: the workman who must get his quantities of material right; the factor who must manage multiple accounts dextrously; the substantial landowner who would redesign his bowling green or compute the value of his shipping interests discounted against time or loss.

Not surprisingly, it was the perspective of the merchant that returned again and again, and international trade was seldom far from view: 30 barrels of anchovies, 71 hundredweight of tobacco, 5 chests of sugar, 3 barrels of indigo. You can almost hear Hutton telling his students (and their parents): See how useful mathematics is, how rich it can make you, how much it can transform your life.

Writing a book was a much bigger step than sending in problems and solutions to magazines, and it demanded much more care. Blunders now would be costlier than wearing an embarrassing garment in a pit village. For the first edition Hutton paid for the printing himself, meaning that he alone bore the financial risk in case the book failed to sell. His patron Robert Shaftoe in fact contributed to the cost in return for the book’s dedication to him. The book was produced by a local print shop, with Hutton reputedly cutting his own type with a penknife when the shop didn’t have the fractions or algebraic characters the book needed.

The Guide was advertised in a number of newspapers, but of direct reaction there was practically none: no reviews, no comment in the press. It faced stiff competition. Even within Newcastle there were other mathematics textbooks being promoted, and other mathematical authors longer established and better known. The Banson dynasty, who dominated the city’s Free Writing School, had been publishing their own arithmetic books since 1709, most recently in 1760. Another northern author had an ‘easy introduction’ to mathematics out in 1763.

Despite that, the Guide found a market. We don’t know how many copies were printed, but a decent stock had sold out within a year or so, and Hutton managed to interest a London publisher in bringing out a second edition. This was good news, and ensured a much wider circulation for the book, this time at no financial risk to the author. His growing reputation was doing its work. By the time of the third edition, in 1771, the advert could say that the little book had ‘been found … useful in schools all over the kingdom’. The Guide , in fact, would run and run: it was still in print in the 1860s. The name of Charles Hutton was becoming harder and harder to avoid if you were interested in mathematics and its teaching.

Contacts in London made a huge difference. After the Guide Hutton devised a new, more ambitious publication project: a book on mensuration. This could have been a subject for another slim textbook on the model of The School-master’s Guide . But Hutton had something much grander in mind. Not a little book of practical rules but a veritable encyclopedia covering every aspect of geometry and its practical use. Hutton took to riding over to the village of Prudhoe at weekends to consult with the schoolmaster there, a Mr Young, who coached him in advanced geometry and mensuration and, it was said, worked over drafts of his new book with him.

Announced in the Newcastle papers in December 1767, Hutton’s Treatise on Mensuration appeared in twenty-eight instalments between March 1768 and November 1770. His publisher diligently promoted it in a range of national and local newspapers. Hutton undertook his own publicity campaign, writing personally to a long list of philomaths culled from The Ladies’ Diary and elsewhere. He obtained permission to dedicate the book to the Duke of Northumberland.

The results were spectacular. When the Mensuration appeared as a single collected volume at the end of 1770, the list of subscribers contained more than six hundred names. Probably amounting to more than half the active mathematicians and lovers of mathematics in the United Kingdom, from Penzance to Dundee, they included two dukes, one earl, and astronomers from Oxford University and the Royal Observatory. Both the English universities and most of the Scottish ones were represented, as were surveyors and instrument makers, schoolmasters and country curates, surgeons, excise officers and Fellows of the Royal Society.