Sir William Petty

Petty, Sir William, M.D., one of the most successful of the many adventurers enriched by Irish confiscations in the 17th century, and a benefactor to Ireland by his survey and his economic writings, was the son of a clothier, and was born at Rumsey in Hampshire, 26th May 1623.

He retired to the Continent during the early part of the civil war, and is stated to have worked as a carpenter at Caen in Normandy.

But he must also have studied medicine, for in 1649, soon after his return to England, he took his degree of Doctor of Medicine at Oxford.

He secured the appointment of physician to the Parliamentary army in Ireland, and landed at Waterford in September 1652, having then a capital of £500.

In this office he continued until 1659, at a salary of £365, making at the same time by private practice some £400 per annum.

In December 1654 he entered into a contract with Government for the survey of Ireland at the rate of £7 3s. 4d. per 1,000 acres of arable land, besides 1d. per acre from the soldiers to whom it was to be allotted.

Mr. Prendergast writes, in his Cromwellian Settlement:

“It was characteristic of the period, that this great step in perfecting the scheme of plantation was consecrated with all the forms of religion, the articles being signed by Dr. Petty in the Council Chamber of Dublin Castle, on the 11th December 1654, in the presence of many of the chief officers of the army, after a solemn seeking of God, performed by Colonel Tomlinson, for a blessing upon the conclusion of so great a business. … The field work of the survey was carried on by foot soldiers, instructed by Dr. Petty, and selected by him as being hardy men, to whom such hardships as to wade through bogs and water, climb rocks, and fare and lodge hard, were familiar. They were fittest, too, ‘to ruffle with’ the rude spirits they were like to encounter, who might not see without a grudge their ancient inheritances, the only support of their wives and children, measured out before their eyes for strangers to occupy; and they must often when at work be in danger of a surprise by Tories. Some of the surveyors were captured by these bold and desperate outlaws, when the sending away of the forces for England and Scotland, about the beginning of the work, left him naked of the guards he had been promised. Eight of them were surprised by Donagh O’Derrick, commonly called ‘blind Donogh’ (who, however could see well enough for this purpose), near Timolin, in the County of Kildare, and were by him and his party carried up the mountains of Wicklow into the woods, and there, after a drum-head kind of court-martial, executed by them as accessories to a gigantic scheme of ruthless robbery.”

The office work of Petty’s survey was carried on in a large house, known as the “Crow’s Nest,” in Dublin, on the site of the present Crow-street, to which it gave its name.

His task was completed in the amazingly short time of thirteen months.

Major-General Larcom, who carried to completion the Ordnance Survey of Ireland in the present century, bears the following testimony to the manner of its execution: Petty’s

“survey will always remain one of the most remarkable undertakings of which we have any record. We are not to estimate its merits as a topographical work by the precision which has been attained in modern times, nor test it by comparison with modern surveys, but with those which had gone before, and which it immediately replaced, as well as the circumstances under which it was executed, and the short time in which the whole operation was performed. … It would be no easy task in our own day, to accomplish in thirteen months, even a traverse survey in outline of 5,000,000 acres in small divisions, and it was immeasurably greater then. … It stands to this day, with the accompanying books of distribution, the legal record of the title on which half the land of Ireland is held; and for the purpose to which it was and is applied it remains sufficient.”

By this survey Dr. Petty, according to his own admission, made some £9,000, which, with other smaller items, including his professional emoluments and his salary as Clerk of the Council in Dublin, enabled him to purchase off-hand some 19,000 Irish acres of land, which twenty years later yielded him as much per annum as the price paid.

By a judicious system of dealings in land, he added still more to his possessions, which included all the country to be seen from the top of Mangerton, in the County of Kerry.

He was returned to Richard Cromwell’s Parliament in 1658.

In March 1659 he was accused by Sir Jerome Sankey, another English adventurer, and a member of the same Parliament, of having “made it his trade to purchase debentures,” he “being then the chief surveyor.”

Petty’s maiden speech was a justification of his conduct.

He appears to have courted the closest scrutiny into all his dealings; but such a storm was raised that Richard Cromwell was obliged to dismiss him from his public employments.

Dr. Petty having made his fortune under the Commonwealth, obtained court favour and rank after the Restoration.

Charles II. was “mightily pleased with his discourse.”

He was knighted in 1661, in 1662 was made one of the Court of Commissioners for Irish Estates, and Surveyor-General of Ireland; and he was returned to the Irish Parliament for Enniscorthy.

“It was,” says John Mitchel, “in the Comity of Kerry that Dr. Sir William Petty had his principal estates. For years the vales of Dunkerron and Iveragh rung with the continual fall of giant oaks. There was a good market; Spain and France were searching the world for pipe-staves; in English dockyards there was steady demand for ship-knees; and Sir William knew exactly where there was the best market for everything. In Ireland itself, also, he set on foot ironworks; and fed the fires from his own woods. … There was no source of profit known to the commerce and traffic of that day in which Sir William did not bear a hand.”

Macaulay gives an interesting account of the difficulties with which his English colony, settled at Kenmare, had to contend, from the forces of nature and the hostility of the inhabitants.

The individuals composing it (seventy-five men and one hundred women and children) were ultimately obliged to take refuge in a fort built on a promontory until the arrival of ships to convey them to England.

In 1667 Sir William Petty married the relict of Sir Maurice Fenton, Bart.

He built a fine house in London, and when drawing up his will in 1685, estimated his income at £15,000 per annum, and his personal property alone at some £45,000.

In Dublin he had founded a Philosophical Society over which he presided.

He was one of the original members of the Royal Society, and a constant contributor to its transactions.

He was the beloved friend of many eminent men, including John Evelyn, who frequently mentions him in his diary:

“If I were a prince, I would make him my second councillor at least.”

Macaulay styles him “the benevolent and enlightened Sir William Petty;” and says he “created the science of political arithmetic.”

He died 16th December 1687, aged 64, and was buried beside his father and mother in Rumsey Church.

The present Marquis of Lansdowne inherits much of his estates. [See notice of Earl of Shelburne, page 201.]

Petty is described as having been “a proper handsome man, measured six foot high, good head of brown hair; his eyes a kind of goose grey, but very short-sighted, and as to aspect beautiful, and promised sweetness of nature; and they did not deceive, for he was a marvellous good-natured person.”

“The variety of pursuits in which he was engaged,” says the Encyclopaedia Britannica, “shows that he had talents capable of achieving anything to which he chose to apply them; and it is certainly not a little remarkable that a man of such an active and enterprising disposition should have found time to write so much as he did in the course of his busy life.”

Twenty-five of his books and essays, chiefly upon scientific and social questions, are enumerated in the notice of him in Wood’s Athenæ Oxonienses. The most important of those relating to Ireland are: his Maps of Ireland, published in London in 1685, comprising a general map of Ireland, the provinces, and counties, in thirty-six plates, with portrait of himself; and his Political Anatomy of Ireland (Lond. 1691), re-published by Mr. Thom in his Tracts Relating to Ireland. This invaluable work gives a minute account of the condition of the country in 1672—its extent, population, and prospects, its resources and political condition.

Sir W. Petty estimated the area of Ireland at 17,000,000 statute acres (14,000,000 tillage and pasture, and 3,000,000 plantation and waste).

The actual area is now known to be 21,000,000 (16,500,000 tillage and pasture, and 4,500,000 plantation and waste).

He estimated the population at 1,100,000 (800,000 Irish, 200,000 English, and 100,000 Scotch; or, 800,000 Catholics, 100,000 Established Church, and 200,000 Dissenters).

It is interesting to remark that in two hundred years the proportion of Catholics has increased from 73 to 76 per cent. of the total population, and of members of the Established Church from 9 to 12 per cent., the proportion of Dissenters having fallen from 18 to 12 per cent.

He estimated the number of families in Ireland at 200,000 (160,000 “with no fixed hearths”); and the number of houses at 40,000, of which 24,000 had only one chimney.

The present number of houses is 1,100,000, of which, as nearly as can be judged, 300,000 have only one chimney.

The originals of his maps can be consulted in the Record Office, Dublin.


14a. Athen&aelug; Oxonienses: Anthony A. Wood, edited by Philip Bliss. 4 vols. London, 1813–’20.

16. Authors, Dictionary of British and American: S. Austin Allibone. 3 vols. Philadelphia, 1859–’71.

110. Dublin, History of the City: John T. Gilbert. 3 vols. Dublin, 1854–’9.

124. Encyclopaedia Britannica. London, 1860.

127a. Evelyn, John, Diary: Edited by William Bray. 2 vols. London, 1819.

142. Froude, James A., Reply to the Falsification of History by: John Mitchel. [Glasgow, 1873.] (Pamphlet.)

223. Macaulay, Lord: History of England, from the Accession of James II. [to 1702]. 5 vols. London, 1849–’61.

284a. Petty, Dr. William: History of the Down Survey, A.D 1655–’6. Dublin, 1851.

284b. Petty, Sir William, The Political Anatomy of Ireland. London, 1691.

324a. Thom, Alexander, Dublin Directories. See also No. 104b, and 183.