104 Transactions. —Miscellaneous. 
experience. Thus the section survey in the southern portion of this colony 
has been proved by mathematical reduction to a general accuracy of within 
two to three links per mile, * while the average error of the surveys of 
British India, where ruled by primary triangulation, is twelve links per 
mile,t and the information that I have obtained directly from officers 
connected with the Ordnance Survey of England shows the error there to vary 
from three to fourteen links per mile. Nor is the cause of this far to seek. It 
lies in the fact that inordinate care and estimation of the refinements of ob- 
servation re-act disadvantageously in the practical work. It reduces the 
status and respectability of the section surveyor, whose office, how- 
ever despised and unimportant in England or India, is all important here. 
Hence the higher accuracy of our actual survey is due to the better class of 
officers employed. | 
But while I say so much at present, it is not to be understood that I 
oppose primary triangulation for all time to come; as the wealth of the 
colony inereases, as learned classes arise, as knowlelpó becomes a pursuit 
for its own sake, as learning advances in our universities, and as our 
scientific societies grow in strength, the subtle and profound problems 
that primary triangulation elucidates will then be usefully and intelligently 
studied. Further, in support of this the legislature may be fairly asked to 
vote the cost of a staff of specially trained officers and assistants. | 
To make myself fully understood on this subject, I may state that the 
main object of the promoters of primary triangulation in Europe and 
elsewhere is to ascertain the figure, dimensions, and specifie gravity of the 
earth, as stated before. With these investigations, in course of time other 
physieal problems and modes of observation have become associated, so 
that in these modern days the system would be held to be incomplete 
were they omitted. Thus originally, with the primary triangulation on a 
: meridian, the zenith sector almost alone was had recourse to for astrono- 
mical comparison of differences of latitude. Now the electric telegraph is 
had recourse to for comparisons in differences in longitude. By this means 
abnormal conditions of the density of the earth, as indicated by pendulum 
operations, have been explained, and certain curious anomalies of the con- 
stitution of the solid crust of the earth have been submitted to mathemati- 
* Exposition of Otago Surveys, p. 16. J. T. Thomson, C.E., F.R.G.S., Dunedin, 1875. 
Report on Surveys of British India, 1871-72, p. 35 
t The State of Massachusetts, the best settled in the United States, having been 
oceupied since the year 1620, now moves for a primary triangulation, but only on purely 
scientific grounds. This is due to the influence of the wealth and intellectual pre- 
eminence of society in that state. See “ North American Review," July, 1875. The Federal 
Government of the United States has allowed a coast primary triangulation to drag its 
slow course for 25 years under great difficulties.—J. T. T. 
