It appears from a report of Colonel Colby, in 1840, that the purposes for which the English and Irish surveys were designed were gradually developed and not all originally known.
The principal triangulation, on which the survey of South Britain had been based, was partly designed for astronomical purposes, and partly for a map on small scale.
The detail plans were commenced by officers of the Royal Engineers, partly for the purpose of practicing them in military drawing, and partly for the purpose of making plans for the use of the Ordnance.
The publication of some parts of this map on the scale of one inch to one mile created a desire among the public to possess better maps than had formerly existed.
This led to the employment of civilian surveyors to advance the progress of the map, and it was found necessary at great additional expense, to revise and correct these contract plans.
The work did not possess the accuracy demanded by the admiralty in forming the basis of their coast surveys for the Geological Survey or the civil engineers. As a military map its publication during war was suspended, and its continuance became a matter of doubt in time of peace.
At one time the gentlemen of Lincolnshire and Rutlandshire proposed to the government to proceed with the map of their district out of its regular turn, upon condition of their becoming subscribers for a certain number of copies. These gentlemen partly wished for the map for their use in hunting, and partly for the improvement of the country in marking out the drainage of the fens.
Prejudices existed, which could be traced back to the Norman conquest and Domesday Survey—against the right of a surveyor to enter a private estate, and in the early contract plans for the English maps the surveyors neglected the survey of the lesser streams, to obviate the inconvenience of trespassing and to save themselves trouble.
These were some of the causes of delay, expense and insufficiency which had operated against the earlier surveys.
The survey of Ireland began in 1825 under far more favorable circumstances than the Ordnance map of England and Wales. The triangulation commenced from a more accurate baseline than any preceding triangulation, and was designed to serve as a basis for any future survey in any scale, however large.