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" an account of the Trigonometrical Surrej^ extending over the 

 years 1800 to 1809, by Lieutenant-Colonel William Mudge of the 

 Ro^^al Artillery, F.Pv.S., and Captain Thomas Colby of the Royal 

 Engineers." This association of his name M'ith that of the Director 

 of the Survey, of itself shows the active part he thus early took in 

 the operations of that important undertaking, and the estimation in 

 which his services were then held. He was elected a Fellow of the 

 Royal Society in 1820, and in 1821 obtained the brevet rank of 

 Major. 



In 1824 Major Colby commenced the great work of his life, the 

 Ordnance Survey of Ireland. In that year a Committee of the House 

 of Commons reported on the necessity of a General Survey of Ireland, 

 and recommended that it should be undertaken by the Ordnance. 

 The Duke of Wellington was IMaster- General, and having assumed 

 the responsibility of such a task, he confided its execution to Major 

 Colby, who had then for some ^^ears conducted the Survey of Great 

 Britain. The survey required for Ireland was very different in its 

 nature and objects from that of Great Britain: it was expected to be 

 laid down and published on a scale of 6 inches to a mile, and was 

 designed to form the basis of a land valuation, and of a revised 

 system of local taxation. For a work of such minute detail and 

 such close precision, as these objects rendered necessary, Major Colby 

 was obliged to create the means of execution and to devise a plan of 

 operations v.diich should enable him to employ numbers as M*ell as 

 skill. Taking for his model the celebrated 'Down ' Survey of Sir 

 William Petty (subsequently so well described by Major Larcom, 

 R.E), and applying thewholeenergiesof his mind to the subject,he de- 

 vised that beautiful system of disciplined and co-operative labour 

 which enabled him to apply to the work all the resources of science, 

 and yet to employ upon it both private soldiers and peasants. The 

 Royal Sappers and Miners supplied the highly-trained soldiers who 

 formed a nucleus for the work, and the quick and intelligent 

 peasantry of Ireland produced numbers of candidates sufnciently in- 

 structed to serve as materials for its perfect construction. To those 

 who saw the work in its infancy, when everything had to be created, 

 and remained to witness it as a vast and beautiful machine, combi- 

 ning into harmonious action the labours of about forty observers and 

 many hundreds of surveyors and draughtsmen, and producing annu- 

 ally a perfected survey of several millions of acres, the success of 

 General Colby must appear most complete and most wonderful. 



To secure the undisturbed and uniform movement of so compli- 

 cated a machine, it was necessary to form an equally perfect office 

 establishment, and this was done in the Survey Office at Mountjoy, 

 in the Phoenix Park, Dublin, the arrangements of which (including 

 those of the Engraving Establishment) were carried by Colonel 

 Colby to the utmost perfection, under the personal superintendence 

 of Captain (now Major) Larcom; and the final excellence of that 

 establishment may be now studied in that of the Map Office at 

 Southampton, which is, in fact, no more than its reflected image. 



