“The Great Arc” contains two stories. The story of the Great Trigonometrical Survey of India and the story of how Everest came to be reckoned the highest mountain in the world. The Great Trigonometrical Survey of India had two purposes: a base for mapping and the measurement of an arc of the earth’s surface for use in geodetic studies. The two men who controlled the survey were contrasting types. William Lambton a quiet unassuming man whose main fault, according to Keay, was that he left too little information for posterity about himself. A rare fault indeed. Lambton initiated the survey, established standards and procedures that he passed on the Everest. Everest recalls Lambton “as display(ing) no symptom of more than common powers... but when he aroused himself for the purpose of adjusting the great theodolite, he seemed like Ulysses shaking off his rags...” Everest was a bombastic, often irascible man who provided the author with a good deal of material for this book. However, he improved some of Lambton’s procedures - like realising horizontal angles could be read more accurately to lights in the evening than flags during daylight - and he continued working through periods of incapacitating illnesses. The language Everest used when castigating his staff - which he did quite often - is described as humiliating, unreasonable, sarcastic and “often ludicrously disproportionate to the supposed crime.” Regarding “such attacks” Keay observes that “some brave souls, noting how the vitriol was neither sustained or consistent, would come to regard them with a certain affection.” Having re-acted in a similar way to similar senior surveyors on several occasions during my working life, I am happy to learn I was a “brave soul” - to so react on those occasions. The story of Mount Everest involves many travellers and surveyors. From the early 1800s British officers began travelling beyond northern India - seeing different peaks and making different estimates of their heights above sea level. Once convinced the Himalayas were higher than the Andes; peaks like Nanda Devi, Dhaulagiri and Kangchenjunga were all, at various times, thought to be the world’s highest. The problem was that observations to the peaks close to sea-level were over distances too long to be accurate while observations closer to the peaks were rendered doubtful by imprecise value of the height above sea level of the observation point. In the 1856 Andrew Waugh (Everest’s successor) using practical knowledge of the relationship between height above sea-level and barometric pressure, came up with the height of 29,002 feet and declared Everest the highest. “The Great Arc” also contains some bad press for surveyors. The high handed manner in which Everest and his teams imposed their survey on the country helped create the atmosphere from which the Indian Mutiny erupted in 1857. In the vicinity of Delhi a faulty reconnaissance resulted in “a gap 30 feet wide” being cut through both a village and a large town. One wonders on the degree of community consultation that took place before this “clearing.” An interesting aspect of surveying arose as the triangulation reached its northern limits - close to the Himalayas. Discrepancies in the triangulation could not be resolved. An adage: when you are confronted by anomaly for which you cannot account, you are on the verge of an important discovery, was invoked. In this case, the “anomaly” led to the “important discovery” that landforms (ie the Himalayas) cause deflection of the vertical. However, based on my own experience, I urge practising surveyors to be reluctant to account for any “anomaly” in their own work as “an important discovery.” Harper Collins. Paperback., R.J.Wenholz Canberra