we give the commencement only; the remainder is there are townlands which were poor and sterile when rather dull:

"Though many a sturdy oak he laid along.

the scale of rating was made, but which have grown more valuable without a corresponding increase having been made in the cess payable by them; so that different townlands pay very unequally in regard to their means. Sometimes a townland, which reaped great advantages from having roads made through it, out of the county funds, did not contribute anything towards those funds, because when the apportionment of the rate was fixed this townland was poor and sterile.

Fell'd by Death's surer hatchet here lies Spong: Posts he oft made, yet ne'er a place could get, And lived by railing, though he had no wit; Old saws he had, although no antiquarian, And stiles corrected, yet was no grammarian." The fine mansion at Ockham is the residence of Lord Lovelace, whose Lady is Lord Byron's daughter Ada. Passing by Wisley, where the Mole and Wey approach within a mile of each other, though they diverge again almost directly, we next reach Byfleet, noted as the residence of Spencer, the author of Anecdotes of Pope,' a dull book, and of Polymetis,' one that, despite the prodigious prosings of Polymetis, and the ever-introduction of improvements in these respects, as well lasting simper of Mysagetes, is rather more amusing, though perhaps hardly meant to be so; he also wrote an Essay on Pope's Translation of the Odyssey, Johnson says of him, in his clever, rough way, "He was a man whose learning was not very great, and whose mind was not very powerful:" a judgment which nobody can deny.

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About 1824 attention was much directed to the state of the roads, the drainage, the canals, and the river navigation of Ireland: and it was at once seen that an accurate survey of the whole island, with its boundaries both artificial and natural, would greatly facilitate the as in respect to a new valuation of the townlands. Accordingly Colonel Colby was directed to suspend for a while his surveying operations in Scotland, and lay the plans for a trigonometrical survey of Ireland on a scale of great completeness. A central office was established at Phoenix Park in Dublin; and Colonel Colby worked out a plan of operation in a manner which none but The next place to Byfleet is Weybridge, a large a military man could devise. There were officers of village, without any remarkable feature. Near it is artillery to superintend large compartments; offiHam House, an old mansion, with some fine cedars in cers of inferior rank under these; and so on down the grounds. It was given by James the Second to to the humblest assistants, each one having the most Catherine Sedley, the daughter of Sir Charles Sedley. exact and distinct instructions of what he was to do, She afterwards married the Earl of Portmore, whose and where his department ceased. It was a most indescendant is still the proprietor of Ham House. The structive example of division of labour; there being at river runs along Oatlands, the seat of Lord Francis times no less than two thousand persons engaged in Egerton. It formerly belonged to the Duke of York, this object, and all directed by the energies of one for whom it was purchased from the Duke of New-mind. The late lamented Lieutenant Drummond castle. The present building is recent, but the site on entered with such earnestness into this vast enterwhich it was erected was formerly occupied by a royal prise, that he is believed to have hastened his death mansion. While it was a royal domain Elizabeth often thereby; for the officers and men who › conducted visited it, and sometimes resided in it. Charles the the out-of-door observations were exposed to wet, First settled it on his queen Henrietta. The grounds frost, wind, heat, dew-and all the alternations of a contain a grotto, said to be the finest in England; it variable climate. was raised at a great expense by the Duke of Newcastle. In the house there is a good collection of pictures.

The river enters the Thames not far from Walton bridge, and nearly opposite the Coway stakes, where Cæsar is supposed to have crossed the Thames in his second expedition. None of the stakes, we believe, remain now. At Weybridge there is a railway station, from which we may be whirled back to London almost as quickly as if we possessed Fortunatus's cap.

THE ENGLISH AND IRISH ORDNANCE
SURVEY.

[Concluded from page 391.].

THE Irish Ordnance Survey, to which we next direct our attention, has been a costly affair; but it is one of the noblest gifts that science ever made to a nation. It was intended originally to facilitate certain fiscal arrangements in rating, but its value will continue as long as the country exists, whatever changes may take place in temporary political arrangements.

About twenty years ago, a Committee of the House of Commons recommended to government the appointment of a body of persons to make a complete survey and valuation of Ireland; the former being the ground-work on which the latter was to be conducted. The necessity for this valuation arose out of certain peculiarities in which Ireland differs from, England. In England various public expenses are borne or managed by local trusts or committees, under the provisions of especial acts of parliament; but in Ireland they are borne by the counties, through the medium of an assessment called a cess. This cess does not press equally on all the proprietors in a county; in some

The first important operation was to lay down a baseline, as a commencement to the triangulation. The ground selected was on the shores of Lough Foyle, near Londonderry, where a base-line nearly eight miles in length was laid down. This line is deemed one of the most accurate specimens of measurement yet produced, perhaps the most accurate. As there were reasons for believing that the deal rods, the glass tubes, and the steel chains used in former measurements were all exposed to errors which it was desirable to avoid, Colonel Colby devised an entirely new piece of apparatus. It is known to most persons that there are clock pendulums so formed of two or more different metals, that the unequal expansions of the one and the other shall be made to compensate each other, and leave the effective length of the pendulum unaltered: now Colonel Colby adopted a similar principle in the measurement of his base line. He caused two bars, the one of brass and the other of iron, to be so connected together that two steel pins should be always exactly the same distance apart, whether the bars themselves expanded or contracted; and this distance between the two points was made the unit of measurement along the line. By means of this piece of apparatus, and other contrivances adopted by Colonel Colby, such an extraordinary degree of accuracy has been attained, that it is computed that the error, if any, cannot exceed two inches in a length of eight miles.

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The base-line being thus established, the triangulation commenced. The formation of the larger triangles commenced in 1825, and finished in 1832. It was in this part of the undertaking that the powerful oxyhydrogen light was adopted by Lieutenant Drummond, as noticed in our No. 514. Three elevated points were

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selected, within view of each other so far as regarded intervening obstacles, but too far apart to be visible without a very intense light; and to furnish this light was the object of Drummond's apparatus. In one instance, three points were selected distant respectively 101, 93, and 86 miles and each one of these was made visible from each of the others.

When the whole kingdom was thus divided by enormous triangles, established with all the resources of refined science, these triangles became subdivided into smaller ones, and these again and again subdivided, until a minute network extended throughout the island. The valuators for the townlands required this minuteness of detail, and the surveyors had to keep this matter constantly in view.

In an account which Colonel Colby sent to the government in 1834, is an enumeration of the persons then employed in the actual survey, classed in a very definite manner. There was the colonel-superintendent himself, captains of two different classes, lieutenants of three different classes, civil assistants in seven classes, sappers and miners in two classes, and labourers. The number altogether was about seven hundred; but since then, when draughtsmen and engravers have been added to the list, the number employed has sometimes reached two thousand. The seven classes of civil assist ants received from one shilling to eight shillings per day, according to the rank they occupied and the nature of their services.

culations have to be gone through to obtain the lengths of the sides of the triangles, which lengths give the distances from place to place; and these calculations are capable, by a little mathematical adjustment, of being brought to such a form that the simplest rules of arithmetic are sufficient for their performance. This humbler species of calculation has been conducted in a singular way. It was stated in the Quarterly Review' for 1841, as an indication of the existence of a love of mathematics among the Irish peasantry, that during the Ordnance Survey boys were found in abundance able and willing to work out these calculations at a halfpenny a triangle.

We may now briefly notice the Maps resulting from this survey. These maps have been published with much rapidity during the last few years, and the series is approaching towards completion. They are published on the magnificent scale of six inches to the mile; a scale whose magnitude can scarcely be appreciated without taking some particular instance. Let us select, then, the county of Kildare. This county is considerably less than half the size of the county of Kent; and yet the Ordnance map of it occupies no less than forty-two sheets of very large size, probably three feet by two. These maps are especially intended to refer to the townland divisions of the county; but their large scale affords facilities for giving other minute details. It is scarcely too much to say that every tree and every house is separately marked. Either by symation is given in a small space. Besides the parishes, baronies, townlands, cities, towns, and villages, all the parish churches, parks, and seats; all the round towers, forts, ruins, and other antiquities; all the bridges, locks, and weirs of streams and canals; all the mines, quarries, wells, bogs, and collieries; all the tanneries, brick-fields, bleach-fields, forges, and lime-kilns, are represented.

The survey and the valuation are two distinct opera-bols or by a peculiar engraved character, much informtions, the latter being dependent on the former for its data, but independent of it in details. As the survey progressed, certain changes in the laws relating to Ireland rendered desirable a minuteness of survey quite unparalleled in such matters. Not only were the general divisions of the country into parishes, townlands, &c. surveyed, but it was deemed expedient to ascertain the exact limits of estates and farms, the quality of the soil, its natural productiveness, and how Such is the scale in which other counties are being far it had been improved by cultivation. But many of mapped out. The county of Fermanagh occupies these details were of a character which could not be forty-two sheets; Monaghan, thirty-six sheets; Louth, engraved on a map: they were printed in a book. A twenty-seven sheets; Donegal, a hundred and twelve volume appeared in 1835, relating to the statistics of a sheets; Meath, fifty-five sheets; Leitrim, forty sheets. portion of the county of Londonderry, as ascertained Sligo and Longford, seventy-eight sheets; Westmeath, by the survey. This book is a quarto volume of three forty-two sheets; King's County, forty-nine sheets; hundred pages. It treats first of the "natural state," Carlow, twenty-eight sheets; Galway, a hundred and such as geology, botany, zoology, hills, lakes, rivers, thirty-nine sheets; and so on. What the total number &c.; then of the "artificial state," such as the town- will be we do not know; but it is easy to calculate, from Jands, antiquities, towns, seats, roads, &c. ; and then of the length and breadth of Ireland, that if the whole the "general state," such as municipality, education, island be represented in the scale of six inches to the legal institutions, &c. It is perhaps one of the most mile (which is now being done), the whole of the sheets minute specimens of statistics ever produced; but the connected together would form a map of Ireland a expense of continuing such a survey throughout Ire-hundred and forty feet high by a hundred and ten in land, and publishing the results, would have been so width! This will indeed be a monument of patience enormous, that government suspended it, with the ex- and skill. ception of the geological portion.

When the British Association held their meeting in Dublin in 1835, the Ordnance Survey and its progress excited much interest. It was stated in one of the public journals at the time, that "To understand the care that has been taken to ensure accuracy, it would be necessary to visit the Ordnance-Office in Phoenix Park, Dublin, and investigate the complicated intellectual machinery by which the detached observations of those employed in the survey are collected and reduced. We use the word 'machinery,' because no other could express the regularity with which the minute division of labour in the several departments is preserved, the strict limitation of every person engaged to his own peculiar branch of business, and the steady union of all in producing a harmonious result." With respect to this division of intellectual labour, it is necessary to remark, that after the surveyors and observers have measured the angles of triangles, cal

The sheets of this gigantic map are sold separately. at an office established by the government in Ireland; the purpose being that those who require to obtain a knowledge of any particular district should be able to avail themselves of the Ordnance Survey at a cheap rate. The charge per sheet is from half-a-crown to five shillings, according to the fulness of the details. The maps having a particular object in view, relative to the townland valuation, are engraved chiefly with reference to the boundaries of estates, farms, &c., without reference to the altitudes, depressions, and undulations of the country, But Captain Larcom, at the Cork meeting of the British Association, described a beautiful mode of "contour" engraving, which was calculated to show at once the precise elevation of any spot: it had been partially acted on, and its efficacy shown.