of Van Diemens Land. 91 



several of the main stations, calculated from entirely inde- 

 pendent observations at those stations, differ in some mea- 

 sure from those derived by means of the triangulation from 

 the observations at Hobart Town. Respectiug this differ- 

 ence I must observe, — 



1st. That the observations on the mountain cannot be 

 considered so trustworthy as those taken in a secure 

 observatory in town. 

 2nd. The probable deviation of gravitation from the true 

 vertical direction may slightly throw out the obser- 

 vations of Elongations taken on the mountain. 

 3rd. The number of observations at each station is not 

 sufficient to give so sure a mean as those taken for 

 the same purpose at Hobart Town. 

 Under these circumstances, and considering the satisfac- 

 tory proofs of accuracy of the triangulation, the latitudes, 

 so far as they have been hitherto calculated by its means, 

 from the initial latitude at Hobart Town, may be depended 

 on in pefrerence to those derived from the local observa- 

 tions. I must mention further, that while all the triangles 

 have been calculated by two or more different computers, 

 those for the latitudes and bearings have not yet gone 

 through this proof, having been only done by myself, and 

 by formulae not giving the most minute results, but such 

 merely as I consider commensurate with the degree of accu- 

 racy to be expected from the character of the observations. 



H. 0. COTTON. 

 1st January, 1864. 



