ConneLL.—On New Zealand Surveys, XXXVI 
such a ease field inspection alone can discover the errors. 
Field inspection may be considered an indispensable part of every sound 
system of survey, and experience has proved that it is only in very excep- 
tional cases that it can be safely dispensed with. 
As the relative position of the trig stations, at which any traverse starts 
and closes, is known, the sum of the reductions of his traverse lines can be 
at once compared with the single reduction of the trig line, and if absolutely 
correct, the two will exactly correspond. In so far as it departs from this 
result, we discover the amount of error in the traverse. 
The traverses, if of considerable length, should also be checked at in- 
termediate points by using the trig lines as bases, and throwing smaller 
triangles on to any portion of the work at intermediate points which it is 
desired to test. 
It is also exceedingly desirable that frequent observations should be taken 
from the stations of the traverse to any trig points in view, and to other 
stations of the traverse, as if this is done it enables a skilful surveyor in a 
few minutes to discover any mistake in the chain-work, such as ten or 
twenty links or a chain dropped in any traverse line, and that without 
going over the work again in the field, though it is always necessary to verify 
by a re-measurement any line upon which an error is thus discovered. 
This, then, is, in my opinion, the chief practical use of the triangulation, 
viz., to furnish a means by which this system of check can be applied to 
the detail survey; and yet the system recommended by Major Palmer 
renders, as I have already shewn, the application of such a check impossible 
in many parts of the Colony for a number of years. No such crucial test 
of the correctness of the detail work of the English Ordnance Survey was 
ever, so far as I can learn, applied, as we are in the daily habit of applying 
to the surveyor’s work in this Province, at least, of the Colony by the above 
method of traverse reduction, and I believe this system is also used in the 
Province of Wellington. 
I have met gentlemen in this Colony apparently familiar with methods 
in use in England, who were palpably ignorant of the way to measure a 
line correctly on the earth’s surface, and who opened their eyes on being 
informed that there was any other way of checking a detail survey save by 
seeing whether it would ‘‘ come in” in the plotting. 
So far as I can read Major Palmer’s report, he does not see the neces- 
sity for any more thorough test being applied to detail work in the Colony 
than that applied in England. 
Referring to revision of old surveys (Report, page 27), he says, if old 
surveys are connected to the trigonometrical points and 7e-plotted in new 
maps, ‘‘ It is not unlikely that.a good deal will be found to fit in such a manner 
