146 



even under the most favourable circumstances, to the Magnetic 

 Meridian. It is obvious that an unalterable meridian to which 

 all bearings are referred, is, in itself, and apart from any 

 triangulation, of very great value ; and when, in addition, the 

 sectional surveys are connected with the stations of a 

 trigonometrical survey, whose relative positions have been 

 accurately determined, a means is afforded by which the 

 boundaries of such sections can be re-established in case of 

 dispute or of obliteration. Such a system is in force in New 

 Zealand and in some of the other colonies — Victoria and West 

 Australia, for example. An accurate triangulation is recognised 

 as an essential and indispensable basis. With this triangula- 

 tion, sectional surveys are connected, and the position of each 

 peg is tabulated relatively to some trigonometrical station. 

 The limit of error allowed for minor triangulation is two links 

 in the mile, and for sectional work eight links in the mile, the 

 great majority of the surveys executed under this system being 

 actually much within the limit. The true meridian for each 

 meridianal circuit, and which governs the triangulations, is 

 observed as the astronomical station of the circuit. Under a 

 correct minor triangulation, the accumulation of errors in- 

 separable from a system of mere traverse surveys built up the 

 one upon the other, and which in a large extent of country 

 must be very considerable, even where the traverse surveys 

 are carefully executed, is avoided, and the error is not carried 

 forward, but is confined to the country between the trigono- 

 metrical stations. The actual error in any circuit traverse, or 

 in a traverse from one trigonometrical station to another, is 

 easily computable by the solution of a series of right-angled 

 triangles, each traverse line being the hypotenuse, and the 

 bearing supplying the angle. 



The system in force in Tasmania, looked at from any point 

 of view, must be regarded as extremely faulty, inasmuch as : — 



(1.) It is not based upon triangulation. 



(2.) The sectional surveys are built up one upon the other, 

 across large areas of country. 



(3.) The surveys are not subject to any mathematical check, 

 such as is afforded by a reduction of the traverses to their 

 co-ordinates on the meridian and perpendicular. 



(4.) There is no systematic field inspection. 



(5.) The limit of error allowed is so great as to preclude 

 anything like accuracy ; the confusion and discrepancies 

 arising from this source alone rendering it impossible to re- 

 establish boundaries, even where an admitted starting point 

 is available, within more than a rough approximation. 



(6.) In the cities and towns there are no standard survey 

 lines laid down from which to define the true frontage lines of 



