166 THE JOHORE SURVEY. 



gulation and traverse methods were combined, a triangula- 

 tion being made of those portions of the country which 

 required to be surveyed in considerable detail, such portions 

 being afterwards connected by traverses. The Johore 

 Survey is the record of a traverse made for the purpose of 

 locating a proposed line, and estimating the cost of a rail- 

 way from Johore Bahru to Segamat, the most southern 

 and northern towns respectively in the territory of Johore, 

 Malay Peninsula. 



Passing on to the consideration of the instruments used in 

 surveying and exploration, they include : — 



1. Those used in the determination of latitude. 



2. Those used in the determination of longitude, either 

 by direct astronomical observation, or by taking the differ- 

 ence between Greenwich and local time with chronometers 

 or rated watches. 



3. Compasses and theodolites, or similar instruments, for 

 taking bearings of the route and of prominent objects 

 contiguous to the route. 



4. Pedometers or passometers for roughly determining 

 distances. 



5. Instruments for determining height above sea level as 

 with thermometers, by boiling, with aneroids or barometers, 

 or with an engineer's spirit-level for exact work. Aneroids 

 are not always reliable, as they are erratic in their behavi- 

 our. Some most valuable observations upon them may be 

 found in Mr. E. Whymper's " Explorations in the Great 

 Andes of South America." 



Besides instruments, and equally important, are the 

 nautical almanack for the current year, one or more copies 

 of which should be provided. 



With regard to the relative merits of chronometers and 

 rated watches, it may be observed that the latter are pre- 



