Connety.—On New Zealand Surveys. XXX1 
various minor triangulations into one consistent whole, and if the Colony 
can afford to spend the money, no one would more heartily rejoice than 
myself to see the work initiated ; but let us be clear about one thing—viz., 
that, until it is completed, such a triangulation cannot replace or do away 
with the necessity for Minor Triangulation or independent bases. Such 
triangulation must go on if the detail surveys are not to be left utterly un- 
checked and unreliable. 
If the execution of Minor Triangulation is carefully attended to, a 
means is at once furnished for checking detail surveys, and the work can 
readily be incorporated with and form a part of a Standard Triangulation, 
whenever it is deemed advisable that such a work should be undertaken. 
I turn now to the consideration of the practical question. To what an 
extent is the extreme accuracy, which we might obtain as the result of a 
Standard Triangulation, in which instruments of large diameter were used. 
affected by the prosecution of a more imperfect, but an immediately avail- 
able system, viz., Minor Triangulation, on independent bases, and carried 
on with portable instruments of five or six inches diameter. 
In order that I may appear to speak about a matter with which I am 
thoroughly conversant, I will take as a sample of Minor Triangulation in 
this Province a portion of work executed by myself and assistants over the 
country between Ohau and Hawea Lakes. This country was exceedingly 
mountainous, the stations varying in elevation above sea-level from 1,100 
to 5,286 feet. The instruments used were five-inch plain theodolites. 
Twelve vernier readings in azimuth were taken at six different parts of the 
lower plate ofthe instrument. A base was measured three times with standard 
welded chain, and due corrections made for temperature near the foot of the 
Ohau Lake, and a base of verification was measured at the south end of the 
Hawea Lake about fifty miles distant from the initial base. 
The result of the angular work was that, taking all the triangles, in 
number above fifty, the average error uncorrected for the minute spherical 
excess on each angle was only three and two-tenths (8°2) seconds, or upon 
the whole triangle, nine and seven-tenths (9°7) seconds. That not more 
than four (4) out of the entire number of triangles, contained in the sum 
of its three angles, a greater error than twenty seconds. 
The length of base of verification was, prior to actual measurement, 
calculated from the triangulation and found to be 37,883-7 links, and the 
result of actual measurement 37,886'2 links, or about four inches and one- 
fifth per mile difference. 
The measurement of this base of vesiialton was completed in the 
presence of the present Chief Surveyor, Mr. McKerrow, who himself made 
the requisite corrections for difference of base and hypothenuse on two steep 
