TRIESTE

TRIESTE, or TRIEST (anc. Tergeste), the principal seaport of the Austrian empire, capital of a government and of the crown land of Illyria, at the head of the Gulf of Trieste, in the N.E. of the Adriatic, 73 miles E.N.E. of Venice. The older part of the town is built on the slope of a hill, which is crowned by the castle; the new town on the level ground close to the semicircular bay that forms the harbour. The former is remarkable for its steep narrow streets and black walls; the latter, separated from it by a broad street called the Corso, is well built and regularly laid out. In the old town the most important building is the cathedral, which stands near the castle on the hill. It is a very ancient building in the Byzantine style, founded in the fifth century, and consists of a nave and four aisles. It has been constructed of fragments of older buildings, and was somewhat spoiled by additions and alterations in the fourteenth century. The tower is believed to stand on the foundations of an ancient temple of Jupiter. In the adjoining churchyard is the grave of Fouché, Napoleon's celebrated minister of police, and that of Winckelmann the antiquary, who was murdered in Trieste in 1768. In the new town, which is divided into two parts by a broad canal, among the principal buildings are the Greek church, richly and brilliantly adorned in the interior, and the Tergestum, a large square edifice containing bazaars, a concert and ball room, exchange, reading-rooms, &c. Since the erection of this building the old exchange, near which is a fountain and statue of Leopold I., has been disused. Trieste has several churches besides those already men-

tioned, two theatres, a custom-house, post-office, hospital, barracks, governor's palace, various schools, &c. The harbour is not without its disadvantages, as it is not sufficiently protected from storms; but it is on the whole good, and has contributed largely to raise the town to its present importance. Its form is semicircular, and it is deep enough to admit large merchantmen to the inner part; but ships of the line have to anchor in the roadstead outside. It is divided into several smaller portions by small piers, and lined with spacious quays. The mole of St Theresa, which has a fort and lighthouse, bounds the harbour on the south, and opposite to it is the new lazaretto, with a basin capable of containing seventy ships in quarantine. Trieste is the only great town of the German confederation on the Adriatic. It is connected by railway with Vienna and other large towns in Germany and Italy; and its many advantages have enabled it to take the place which Venice formerly occupied as the great commercial mart in this part of Europe. The number and tonnage of vessels that entered and cleared at the port in each year, from 1852 to 1857, were as follows:—

The value of the imports and exports from 1850 to 1855 was as follows:—

The navigation is chiefly under the Austrian, Neapolitan, Papal, and French flags; and the principal exports are metals, linen and woollen cloth, calico, hemp, wool, hides, furs, timber, tobacco, corn, rice, wine, and oil; while cotton, silk, raisins, wheat from Odessa, and all kinds of colonial produce, are the articles most largely imported. The Austrian Lloyd's Steam-boat Company, formed in 1833, is one of the principal establishments of the town. It has forty or fifty steamers, which ply between Trieste and the principal ports in the Adriatic, the Levant, and the Black Sea as far east as Trebizond. Trieste has some importance as a manufacturing town, though it is chiefly remarkable for its commerce. Shipbuilding is carried on to a large extent, and there are several extensive docks for that purpose. There are also made here earthenware, leather, wines, spirits, soap, white lead, &c. The inhabitants of Trieste are a motley multitude, collected from almost all countries of the world; Germans, Italians, Greeks, Jews, Armenians, English, and Americans. A great variety of languages is heard, but Italian is the most common, except in the public offices, where German is spoken; and among the peasantry, who use a Slavonic dialect. The ancient Tergeste existed in the time of the Romans, but was then a place of no great importance, being out rivalled by the neighbouring town of Aquileia. In the middle ages, Venice was the great seaport and commercial mart in this part of the Adriatic; and Trieste did not rise to its present importance till about the middle of the eighteenth century, when the enlightened policy of Maria Theresa conferred on the town many favours, and laid the foundation of its commercial greatness. Pop. (1852) 70,846.

This designation is usually applied to those surveys of a country which are effected by means of trigonometry. It is well known that when the base of a triangle has been measured or calculated, and the angles at the ends of the base have been measured, this science affords the means of ascertaining the length of the two remaining sides. (See TRIGONOMETRY). The distance, therefore, between two points on the surface of a country having been measured for a base, and the angles which it forms with some third point, taken as the vertex of the triangle, having been measured, the length of the other sides can be calculated. These sides will then serve as the bases of other triangles, the length of whose remaining sides may in the same way be ascertained; and by thus extending a series of triangles over a country, its dimensions may be obtained with the greatest accuracy.

Any survey carried on from a measured base, by means of angular measurements, may be called a trigonometrical survey; but the term is usually confined to such as extend over a considerable extent of country, and require a combination of astronomical and geodetical observations. When conducted on a large scale, and when extreme accuracy is required, the work, simple in itself, becomes one of immense labour and ingenuity. When it is necessary to have regard to the curvature of the earth's surface, the effects of temperature, refraction, altitude above the sea, &c., in order that minute accuracy may be attained, not only is the utmost care necessary in observation, with instruments of the very finest character, but long and intricate processes of calculation in the highest branches of mathematics are involved.

The fundamental operation, and the one demanding the greatest degree of accuracy, is the measurement of the base line, for an error committed here will affect all the distances deduced from it,—triangulation doing nothing more than determining how many times, or fractions of a time, the measured base is contained in the observed distances. To measure a line 5 or 6 miles in length, so that the greatest possible error cannot exceed a very few inches, is manifestly a work of extreme care, and requiring instruments of the very finest description. In order to insure the greatest possible accuracy of observation, it has been usual, in the survey of this country, not only to observe each angle a considerable number of times, but also from each point to observe the angular distances of all the other principal stations which are visible from it. The discrepancies that then arise are reduced to the nearest probable mean by the theory of probabilities. The degree of accuracy that may be attained by such measurements is shown by the fact, that the length of the base on Salisbury Plain, as calculated by means of a series of triangles, extending from the Lough Foyle base, in the north of Ireland, differed only about 5 inches from its measured length.

The object of a trigonometrical survey may be either to ascertain the form and extent of a country, with the relative distances and bearings of its principal points, for the purpose of constructing an accurate map; or to determine the figure and magnitude of the earth by ascertaining the curvature of a given portion of its surface. The latter of these objects having been already sufficiently noticed under FIGURE OF THE EARTH, we shall confine our attention in the present article to the former; and perhaps the subject cannot be treated better than by giving an account of that great trigonometrical survey that for the last three quarters of a century has been carried on in this country under the direction of the Board of Ordnance, and which is, undoubtedly, the most magnificent work of the kind that has hitherto been attempted in any country. We shall first, then, give a brief historical sketch of that great undertaking, and afterwards some account of the manner in which it is carried out.

Trigonometrical Survey.

The first Government trigonometrical survey in Great Britain History was commenced in the Highlands of Scotland in 1747. After the suppression of the rebellion of 1745, government directed its attention to the establishment of military posts, and the opening up of roads of communication in the remoter parts of the Highlands. Lieutenant-General Watson, who was stationed at Fort Augustus, with the view of carrying out these objects, conceived the idea of at the same time making a map of that part of the country; and the sanction of the Duke of Cumberland having been obtained, operations were forthwith commenced, under the direction of General Roy, the assistant quarter-master-general. Though the work was at first intended to comprise only the Highlands, it was subsequently extended to the Lowlands, and at length included the whole of the mainland of Scotland. The war of 1755, however, put a stop to the undertaking, and the map was never published. General Roy afterwards characterised it as "a work of considerable merit, though, from having been carried on with instruments of a common, or even inferior kind, it is rather to be considered as a magnificent military sketch than a very accurate map of a country." On the conclusion of the peace of 1763, the subject of a general survey of Great Britain engaged the attention of government, but the breaking out of the American war prevented any steps being taken to carry it into effect.

The present undertaking dates from the year 1783, when, on the conclusion of the peace in that year, a memorial drawn up by M. Cassini de Thury, the French astronomer, was presented to the English government, recommending a trigonometrical measurement of the distance between the observatories of Paris and Greenwich, with a view of determining the exact difference of longitude between them. The proposal having met with the warm approval of the Royal Society, to whom it was referred, government agreed to carry it out, and General Roy was appointed to superintend the operations.

The first step in the process was the accurate measurement of a Hounslow base; and, in order that this might form the basis of any future Heathbase survey of the United Kingdom, it was resolved that it should be done with the utmost possible care, and with the best instruments that could be furnished by Ransden, at that time acknowledged to be the first maker in the world. Hounslow Heath, which, besides its proximity to the capital and Greenwich Observatory, presented the advantages of great extent and levelness of surface, free from local obstructions, was selected as the site for a base, and a line upwards of 5 miles in length was marked off for measurement. Up to that time, deal rods had been generally employed in the measurement of those bases in other countries that had been effected with the greatest appearance of care and exactness; and three such rods, of the best seasoned timber, were carefully constructed, each 20 feet 3 inches long, tipped at each end with bell metal. The preliminary operations having been completed, the measurement was commenced about the middle of July 1784. The weather proved wet and unfavourable, and, before the measurement was half completed, the deal rods were found, notwithstanding all the care that had been taken in their preparation, so liable to sudden and irregular variations of length from the state of the atmosphere, as to afford little assurance that that accuracy would be attained which was desirable. As, however, so much of the work had been done, it was resolved to complete it, so that the result obtained might afterwards be compared with that given by more accurate instruments. The measurement with the deal rods being completed, and allowance made for expansion, the distance between the centre of the pipes terminating the base, reduced to the level of the lower extremity at Hampton Court, and at the temperature of 65°, was found to be 27,405.26 feet of the standard scale from which the lengths of the measuring rods were laid off.

At the suggestion of Lieut.-Col. Calderwood, hollow glass rods were next adopted. Three of these, about an inch in diameter and upwards of 20 feet in length, were selected and placed in cases to which they were made fast in the middle and braced at several other points, so as to prevent them from bending or shaking, but allowing them freely to expand or contract. At one end of each rod was a fixed apparatus or metal button, and at the other a move-

Trigonometrical Survey. able apparatus or slider, pressed outwards by a slender spring. In contacts the fixed extremity of each rod was pressed against the moveable apparatus of the preceding, until a fine line on the slider was brought into exact coincidence with another fine line on the glass rod, in which state the distance between the extremities was exactly 20 feet. The new measurement was commenced on the 18th and concluded on the 30th of August 1784. After the rate of expansion of the rods had been determined and allowed for, the length of the base in temperature 62°, reduced to the level of the sea, was found to be 27,404.0137 feet, or 5.19 miles.

1787. The triangulation was not proceeded with till the summer of 1787, when Ramsden had completed his theodolite for the measurement of the angles. This was the finest instrument of its kind that had yet been constructed, having its horizontal circle 3 feet in diameter, and was the first to show that, in consequence of the spherical form of the earth, the sum of the three angles of a triangle on its surface exceeds that of two right angles. The same year Messrs Cassini, Mechain, and Legendre, distinguished members of the French Academy of Sciences, met General Roy at Dover, and the connection was established between the triangulation of the two countries. In order to ascertain the accuracy of the operation, a base of verification was measured on Romney Marsh, near the termination of the triangulation, and was found to be 28,535 feet 8.128 inches, at temperature 62°, and at the level of the sea. The measurement was made by a steel chain 100 feet in length, constructed by Ramsden, and of which the accuracy had been previously tested by measuring with it a portion of the Hounslow Heath base simultaneously with the glass rods. The measured length was found to exceed the computed length by about 28 inches, which was probably as near a coincidence as was to be expected, and may be taken as a conclusive proof of the general accuracy of the whole of the operations.

The illness soon after this of General Roy, followed by his death in 1790, seem to have for a time put a stop to any attempt to extend the operations already begun to a survey of the whole island. Indeed, the renewal of operations is ascribed to the accidental circumstance of the Duke of Richmond, as Master-General of the Ordnance, having purchased a very fine theodolite by Ramsden, similar to that used by General Roy, but with some improvements; as also two new steel chains of 100 feet each, by the same great artist. This theodolite is said to have been ordered by the East India Company for the purpose of surveying their possessions in the East, but some misunderstanding having arisen about the price, the directors refused it, and it was thrown upon the hands of the artist.

1791. In 1791 the Ordnance survey was commenced under Colonel Williams (Captain Mudge of the Royal Artillery, and Mr Dalby, by the remeasurement of the base on Hounslow Heath. Instead of measuring rods, the two steel chains already mentioned were used. Each chain consisted of 40 links of 2½ feet each. At first both chains were used in measuring, but afterwards one only, the other being kept as a standard by which the measuring-chain was compared. In the act of measuring, the chain was laid out in a succession of deal coffers, supported by trestles and stretched by a weight of 28 lbs. After all reductions had been made, the length of the base by the new measurement was found to be 27,404.3155 feet, or about 2½ inches greater than by General Roy's measurement with the glass rods. The mean of the two results, or 27,404.2, was therefore assumed as the true length of the base in the future calculations.

In prosecuting the survey, it was resolved, in the first instance, to carry a series of triangles southwards from the base, in order to ascertain the position of some of the principal stations on the seacoast; and also to determine the length of a degree of longitude by measuring the distance between Beachy Head on the coast of Sussex, and Dunnose in the Isle of Wight,—two stations lying nearly east and west of each other, above 64 miles apart, and visible from each other in clear weather. An opportunity would also thus be afforded of connecting this series with the triangles of General Roy, and of thereby testing the accuracy of both operations. The triangulation was commenced in 1792, and the principal work of the following year was determining the directions of the meridians of Dunnose and Beachy Head. In 1794, a base of verification was measured on Salisbury Plain by steel chains, in the same manner as on Hounslow Heath, the one being used for measuring, and the other kept as a standard. After making the different reductions, the correct length of the base was found to be 35,574.4 feet, and on computing the distance by means of different combinations of the triangles from the Hounslow Heath base, the greatest and least results were found to be 35,574.8 and 36,573.8 feet, the mean being 35,574.3 feet, or about one inch short of the measurement. The distance between Beachy Head and Dunnose, as deduced from a mean of four different series of triangles, was found to be 339,397.6 feet (= 64.28 miles), and the greatest difference from the mean was less than four

feet. On computing from this and the observed angles made by the straight line joining the two stations with the meridians at each, the length of a degree of the great circle, perpendicular to the meridian at latitude 50° 41' (nearly that of the middle point between Beachy Head and Dunnose), was found to be 61,182.3 fathoms = 357,093.8 feet; and hence the degree of longitude at the two stations (which is found by multiplying the degree of the perpendicular circle by the cosine of the latitude) was obtained as follows:—Beachy Head, 232,312 feet; Dunnose, 232,314 feet, the assumed latitudes being, respectively, 50° 44' 24" and 50° 37' 7" (see FIGURE OF THE EARTH).

During the years 1795 and 1796, the triangulation was continued along the coasts of Dorsetshire, Devonshire, and Cornwall, to Land's End. The operations of 1797 commenced with the observation of the pole-star at Black Down early in April; and in the course of the summer the great theodolite was taken to twenty-one other stations, at which the angles were determined, all included between the meridian of that station and St Agnes Beacon. It was judged inexpedient to carry the operations from this point into the north of Devonshire until a new base had been measured, the triangles at present being dependent upon those made in Cornwall in the previous year. In 1798, a series of secondary triangles was observed for completing the survey of Kent and Essex; but the principal operation of the year was the measurement of a new base of verification on King's Sedgmoor, in Somersetshire. This measurement was conducted, like those on Hounslow Heath and Salisbury Plain, by steel chains—only, on account of the irregularities of the ground, it was thought expedient to have a new chain of 50 feet for those parts where the longer chain could not well be used. The reduced length of this base was found to be 27,680 feet, or nearly 5½ miles, and it was supposed by Captain Mudge that the amount of error could not exceed nine inches.

The measurement of an arc of the meridian had been contemplated from the commencement of the survey, but was delayed for some years on account of the zenith sector with which the celestial arc was to be determined not having been completed by Mr Ramsden, whose health was then declining, and who in fact died before the instrument was altogether finished. The meridional line passing from Dunnose to the mouth of the Tees was that selected, as being the freest from obstruction and of sufficient length. The point selected for the northern extremity was Clifton, a small village in the vicinity of Doncaster, nearly on the meridian of Dunnose; and a plain of sufficient extent for the measurement of a base of verification was found at Misterton Carr, in the northern part of Lincolnshire. The two extreme stations were connected by a chain of twenty-two triangles, lying nearly in the direction of the line to be measured. Of these, eleven, extending from Dunnose to Arbury Hill, near the middle of the line, had already been observed, and their sides computed from the Hounslow Heath base; the angles of the remaining eleven were measured in 1801 and 1802, and the distances computed from the new base. The base on Misterton Carr was measured in the same manner as Sedgmoor, and after making the necessary reductions, the length was found to be 26,312.7 feet. As the correct determination of this base was of great importance, every precaution was taken to insure accuracy, and General Mudge was of opinion that the error in excess or defect could not exceed two inches. On computing the distance between Arbury Hill and Corley, near the middle of the arc, by the first eleven triangles, it was found to be 117,463, and by the other eleven triangles, from Misterton Carr, 117,457.1 feet, a difference of less than six feet, upon an extent of somewhat more than 22 miles; a discrepancy which cannot be considered great, seeing that the length of the whole line from Dunnose to Clifton is nearly 200 miles. Had the computation been carried on from Dunnose to Clifton, the length of the base on Misterton Carr, as deduced from Hounslow Heath, would have been found to be only about one foot greater than its measured length. The whole length of the arc from Dunnose to the parallel of Clifton was found to be 1,036,337 feet, or 196.25 miles.

In 1806, another base was measured on Rhuddian Marsh, near St Rhuddian Asaph, North Wales, in the same manner as the former. After Marsh base the necessary reductions were effected, its length was found to be 24,514.26 feet. As evidence of the agreement between that and former measurements, it was found that the distance between Castle King and Weaver Hill (two stations in Staffordshire), as computed from the base on Misterton Carr, was 111,144.1 feet, and 111,148.4 feet, as computed from the new base on Rhuddian Marsh; the difference in a line upwards of 21 miles in length being only 4.3 feet. From this base several series of triangles were carried in different directions. One series extended to Anglesea, and thence by Snowdon down the western coast of Wales, joining, near Aberystwith, a series proceeding from the triangles formerly observed in Gloucestershire. A second series proceeded southward from the base, and joined the southern triangles in Glamorganshire.