4o8 



Report S.A.A. Advancement of Science. 



personal factor, e.g., variable pull on the tape, rather than any 

 errors in the measurement of angles when the instrument is properly 

 used. 



Finally, in considering the record of other data (d), the writer 

 is of opinion that, from the way in which the information has been 

 forwarded to him, there is a loose appreciation of this most important 

 part of a mine surveyor's duty. Minute and careful offsetting is, in 

 the writer's opinion, so much waste of time. By noting the position 

 of benchmark, in hanging of drive relative to the track, and sketching 

 in the contour of the drive as the surveyor walks along, say in 

 winding up his tape, a suflficiently accurate representation of the 

 drive can be obtained on the scales of i 1500 or i :iooo, at which 

 most plans are plotted. The intersection of any fault with the drive 

 is noted in similar manner as the tape is being wound up, whilst 

 the fall or rise of reef in the drive is of no import until the reef 

 enters or leaves the drive. 



We now come to : — 



II. Methods of Calculation. 



(l) does not feel justified in giving his method as the representative one 

 of his group. He remarks that he uses Gurden's Traverse Tables and natural 

 sines and co-sines as a check. 



(2) gives the following : — (Square section paper.) 



Fair Copy 



of Mean 



Angles read. 



E— F— G 



Dip and dis- 

 tance 



Red. level 

 G. Rail... 



E— F 

 360. 6.45 

 179-53.45 



Bearing 



and 

 Distance. 



179.47. 

 293-35.50 



147.75 

 49.20. 



I5I2.IO 



96.30 

 293.22.50 



473.22.50 



i8o 

 293 



Seven Fig. Logs. 



2.1695275 

 9.8 1409 1 2 

 1.9836187 



96.30 

 Hor. 



1.9836187 

 9.9627903 

 1.9464090 



88.39 



+ 55743.77 



55655-38 



2.1695275 



9.8799634 

 2.0494909 



112.07 

 Vert. 



1.9836187 

 9.5986115 

 1.5822302 



+ 38.22 



75653-76 

 75691.98 



Check by Naturals. 



