VI.—Two Skeletons, dis-articulated and Mounted for Teaching Purposes.

1. New-born Lamb (Ovis aries, Linn.).

The bones are all separated from one another, their mutual relations being disturbed as little as possible : they are removable either separately or in groups. The more important cartilaginous parts, such as the external cars, mesethmoid, sternum, sternal ribs, and epiphyses of the long bones, are preserved by the glycerine jelly process.

Prepared by F. E. Bourne.

2. Red Cod (Lotella bacchus, Forst.).

Mounted in much the same way as the preceding skeleton. The entire brain-case of another specimen is placed on the stand, and has the various bones distinguished by colour.

Prepared by E. Jennings.

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Survey Department, Wellington.

Until the abolition of the provincial system of government in November, 1876, the surveys of New Zealand were conducted by nine survey departments, each independent of the other, and working on no common system. At that date an amalgamation into one department was accomplished. Several of the provincial services had conducted their surveys on a page 45 trigonometrical basis, but, as the others were building one survey on another by traverse on magnetic or other azimuthal bearings, without any reference to true meridian or the independent check of triangulation, a state of considerable confusion and uncertainty had arisen in the survey records, which was aggravated by very heavy arrears of land purchases waiting demarcation of boundaries.

Under these circumstances it was necessary to devise a system that would rapidly bring the surveys under control and record, so that settlers might be placed in secure possession of their land, and the Crown be safe to issue titles on reliable plans and descriptions.

At first it was proposed to begin from one or two bases, extending a major triangulation over the country, to be subsequently broken down into a minor, to giving starting and closing points of connection for the Settlement and Land Transfer surveys. But, as the most favourable estimate assigned ten years to this work, it had to be discarded in favour of a more rapid means of overtaking the numerous surveys, awaiting and in progress, scattered over thirteen degrees of latitude, and a territory of 104,000 square miles.

The plan adopted was to divide the country into twenty-right districts, designated meridional circuits. At the initial or main station of each the astronomical meridian was determined from observations of circumpolar stars, and the latitude from observations of stars N. and S. of zenith. Lines of bearings on the true astronomical meridian of the initial station were extended throughout its circuit to the plains and valleys, where surveys were in progress. Within three years these standard bearings had been so extended as to enable all the surveys to be conducted on the true meridian of their respective circuits; for, following immediately on this operation, a base-line was measured, and a minor triangulation of two and three-mile sides, starting from one of the stations of the standard bearings, was spread over the country wherever most required for the check and connection of the settlement surveys. In this way the Colony was placed very quickly under a system of correct recordable survey, readily adjustable to the requirements of a population rapidly spreading over areas page 46 widely apart. The intervening spaces have since been filled in, and it is found that the triangulations close on each other within a limit of error very rarely exceeding two links to the mile, a result which must be deemed satisfactory, considering the number of officers engaged, and that the network of triangles is a continuous chain extending over the Islands from north to south a distance of 1,000 miles. Simultaneously with the minor triangulation of the country, a topographical survey was carried on, giving the positions of rivers, plains, mountains, forests, best lines for future roads, altitudes of valleys, passes and mountains, and generally a correct representation of the features of the country to a scale of 2in. to the mile. In a new country this class of topographical survey is indispensable to an intelligent administration of the settlement of the Crown lands, in the selection of sites for towns, settlements, and public reserves. Without it very great mistakes have been made in parting with sites and frontages, which practically are now irreparable. The cost of the combined operation of trigonometrical and topographical survey, including mapping, averages a little over 1d. an acre. (See the annual Survey Reports of New Zealand.)

Settlement Survey.—This, as the name implies, is the marking off the land purchases already made, or the subdivision by survey of the Crown lands into areas for future selection. The surveyor, aided by the topographical map of the district, makes a careful examination of the country, selecting and grading, if need be, the most suitable main and occupation lines of road which he traverses, proving the accuracy of his work by beginning on one of the stations of the minor triangulation and closing on another. This satisfactorily done, the sectioned areas are designed so as to fairly distribute road-frontages, water-supply, and natural advantages to the several sections. The boundary-lines of sections are marked at each corner by stout pegs and by lock-spits, with additional pegs and lock-spits on the lines giving the range from the road-frontage. Lithograph plans of these surveys are published, showing road-lines, number of sections, areas, streams, and natural features, thereby enabling settlers to find their purchases or make selections without any chance of mistake.

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Instruments.—In the extension of bearings in the meridional circuits and in the triangulation of mountainous districts, and in the connection across Cook and Foveaux Straits, 8in. and 10in. theodolites were used; but where the sides are only two or three miles, as in the districts to be closely settled, 5in. theodolites are found quite satisfactory, each of the three ingles of every triangle being observed at least three times from different zeros, thereby giving six or more readings of the verniers on as many different parts of the limb. The reciprocal vertical angles between the respective stations are also observed and the altitudes deduced. With care, no greater discrepancy than 2ft. should appear as between the determination of the altitude of any station of a triangle from the other two. As a matter of fact, it has been proven frequently on the close of the triangulations on each other that the computed altitudes of the stations common to both do not differ more than 4ft. or 5ft. even when the origins were a hundred or more miles apart.

Measurement of Base and Traverse Lines.—In the measurement of lines the linked chain has been superseded for several years by the steel tape and wire adjusted at 62° Fahr. to he standards laid down by brass scale and beam compass it the head office.

In base and verification lines the ground is cleared of surface regularities, the steel tape is stretched with an even strain, he terminals are marked by a fine puncture on lead, the inclination of surface and changes of temperature noted and allowed for, and the measurement repeated three times alternately from opposite ends of base.

In transverse lines there is no preparation of surface, but the ingle of slope is taken, also the temperature, and the corresponding corrections made. In bush and rugged country the work is greatly expedited by using piano-wire in four or five-chain lengths. It is very light, is unwound from a reel, and stretches taut across rivers, gullies, or uneven surface. The error allowed in traverse is eight links to the mile; but since he introduction of the steel tape and wire, the error rarely exceeds four links even in the most difficult circumstances. See Survey Reports.)

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Record and Reduction of Survey.—For convenience of record the country is divided into survey districts of 12½ miles, or 1,000 chains square, and then again into survey blocks of 3? miles, or 250 chains square. The trigonometrical and topographical sheets of the survey districts are to a scale of 2in. to the mile, and the survey blocks, which contain the working plans of the subdivision for sale and settlement, are to a scale of 8in. to the mile. The sheets are of a uniform size of 3oin square, and are kept flat in portfolios on shelves in fireproof rooms.

The reduction of the trigonometrical stations is made on the meridian and perpendicular of the initial station of the circuit, or the initial station of the survey district, according to circumstances. The traverse-lines of the survey blocks are reduced to one of the trigonometrical stations in the survey block. These reductions are tabulated, and, being all connected and held in one complete network of check, serve ever after as an unmistakable means of rehabilitating the survey, should boundaries become obliterated or be challenged by rival landowners.

In a colonial survey it is of the first importance that all surveys should stand the mathematical test of reduction to the meridian and perpendicular of a governing trigonometrical survey, for, unlike the surveys of old countries, where time-honoured landmarks and a settled population conserve boundaries, the surveys of a new country have no such aids, but, instead, have to create boundaries in the unoccupied wilderness, which at best can only be marked by perishable surface-marks. Then, again, the frequent changes of ownership of land in the colony, facilitated by the Land Transfer system, and the responsibility of the Government in guaranteeing all titles under it, are cogent reasons why the old system of plot and scale should give way to the more rigid mathematical system of reduction of traverses to the meridian and perpendicular of the stations of a trigonometrical survey.

Publications of Surveys.—For the convenience of the surveyors engaged in the Crown Land and Land Transfer surveys the portion of the trigonometrical survey covering each survey district is published and distributed to afford ready data page 49 for the control and check of the traverses. The block sheets are also published, principally for the information of settlers, on a scale of 4in. to a mile; and after the block and section survey of a survey district is completed it is published on a scale of 1in. to a mile. This scale is very suitable for local and rating purposes, for it shows clearly all properties over five acres, the roads, railways, and sites of towns. When necessary the sheets, which are 12½in. square, can be pieced together and a large area of country shown without having a plan of inconvenient size.

Geographical maps on the polyconic projection, to a scale of 4, 8, and 25 miles to an inch, are issued from time to time as the trigonometrical and topographical surveys supply details. The initial station for these maps is a point in the City of Wellington known as Mount Cook, and situated on a public reserve. Its latitude has been determined from observations of stars N. and S. of zenith, observed by means of the zenith telescope; and the longitude from electric signals exchanged with Sydney Observatory. Formerly the longitudes of New Zealand were based on those of the Admiralty survey of the coast, and on absolute determinations deduced from observation of moon-culminating stars. There is such near agreement between all the determinations as practically to make little or no difference in the geographical maps. (See New Zealand Survey Report for the twelve months ended the 30th June, 1884.)

Geodetic.—Although the main object of a colonial survey is to enable the settlement of the Crown lands to proceed on a system of survey and record which, for the settler, will give him possession of a definite piece of land which cannot ever after be overridden by a rival claim, and for the Crown the assurance that its guarantee of title will not involve it in embarrassing claims for compensation through overlapping boundaries; yet the very precision necessary in such a system of survey gives the opportunity of at least verifying the scientific deductions which have been already made in the surveys of older countries, undertaken mainly for geodesical purposes. Thus, the discrepancies between the astronomical and geodetic differences of latitude detailed in the New Zealand Survey Reports, 1880-81 to 1884-85, as existing between stations, shows that in New Zealand the same apparent irregularities in the density of the page 50 earth exists as have been discovered in India and other countries where this subject has had special investigation.

General.—Further information regarding the survey system of New Zealand may be had by consultation of the Annual Survey Reports from 1880-81 to 1884-85, from "The Regulations and Instructions," and from the maps and plans, all of which are on exhibition.