THE JOHORE SURVEY. 179 



observations to a point placed at a higher level than that 

 of the observer, it is necessary to multiply the " generating 

 number," that is, the difference of the staff-readings multi- 

 plied by the constant, by the cosine of the angle of elevation. 

 The author said that from his experience of trigonometrical 

 work of all kinds, as well as of tacheometry, he was of 

 opinion that for most longitudinal and cross-section work, 

 more especially for marine work, the tacheometer was much 

 to be preferred to the "level, theodolite, and chain," both 

 as regards expedition and economy of chain-men, and in some 

 cases of an assistant, where, for instance, two theodolites are 

 being used to intersect the position of an object. 



Mr. Thomas Morgans, in inviting discussion on the 

 questions raised, complimented the author both upon his 

 previous and his present paper. The latter one was of a 

 rather technical character, but it was evident that the author 

 was au fait with the subject with which he was dealing. 

 The Chairman, who spoke at considerable length, was 

 followed in the discussion by Messrs. Pearson, Stagg, 

 Watts, Statesbury, Thompson, and A. P. I. Cotterell. The 

 author, in replying at length to the various questions, 

 remarked among other things that he had the honour of 

 knowing Mr. James Simms, and had the pleasure of going 

 over his works and of inspecting the whole course of manu- 

 facture of the fine instruments which, thanks to the 

 courtesy of Messrs. Troughton & Simms, as also of Messrs. 

 Husbands, of Bristol, they then had the opportunity of 

 inspecting. It might be a matter of gratification to them 

 to know that though they saw so many things imported 

 from Germany, Belgium, and other countries, English 

 mathematical instruments still maintained their old supre- 

 macy, and it was a fact that the larger number of survey- 

 ing instruments used by Continental engineers were 



