An Underground Traverse. 4^9 



forward for calculation of latitudes and departures, the logarithmic 

 calculations of which always decide the value in preference to 

 decimal points of check. 



The writer is of opinion that this method of calculation will 

 ensure that mechanical check of accuracy so necessary in results of 

 this importance. From long practice he has found that the calcula- 

 tion of any one point takes about ten minutes. The method of 

 procedure takes a varying amount of time, according to the amount 

 of accessory data the surveyor may find necessary to note down. 

 On the average, ten minutes at any one station, is about an average 

 time, when native assistants are hanging plumb bobs whilst surveyor 

 is levelling the instrument. 



The writer cannot conclude without hoping that, though he 

 has made free use of information which several individual mine 

 surveyors have supplied at the request of their Consulting Engineers, 

 it will be felt that he is grateful for the trouble taken in forwarding 

 this information. As several have asked that no names might be 

 mentioned, the writer can only tender his thanks collectively to both 

 the Consulting Engineer of the Group and the individual surveyors. 



To the members of this Association his apologies are due for 

 bringing to their notice so much that savours of text-book work. 

 The writer feels, however, that by placing these deductions on record, 

 the attention of many mine surveyors may be called to the want of 

 coherence in their work, which may result in some practical good. 



