BY L. F. GIBLIN, E. L. PIESSE, AND H. R. HUTCHISON. 9 



1913. 



The instrument used was a 5 -inch Troughton and Simms 

 transit theodolite reading on each circle by two verniers 

 to 20". The angle obtained at each setting is given below. 



The degree of accuracy of the angles appears from the 

 triangles ACD, CDT, in each of which all three angles 

 were measured. The sum of the measured angles of the 

 triangle ACD is 180^ 0' 17", and the sum of the measured 

 angles of the triangle CDT is 179^ 59' 53". For the 

 vertical angles, a test of accuracy is given by the angles 

 between A and C and between A and Z>, which were 

 measured in both directions. After applying the usual 

 correction for curvature and refraction, the difference 

 between the angles A to C and C to A is 51", and the 

 difference between the angles A to D and D to A is 3". 

 A test of the accuracy of the angles and measurements of 

 length combined is obtained by calculating the distance 

 from the trigonometrical station to Legge Peak, first from 

 the Stacks Bluff base and the angles observed there, and 

 second from the Nile gorge base and the angles observed 

 at it. The results are 35,280 feet and 35,260 feet, whence 

 it appears that the lengths required for determining the 

 difference of height are known with sufficient accuracy. 



From the abstract given below of the calculations, it 

 will be seen that the height of Legge Peak was deter- 

 mined in four ways calculated in pairs from independent 

 observations at the two bases. The results are: 



Height of Legge Peak. 



These results and the result (5158) feet obtained in 1911 

 justify the adoption of 5160 feet as the height of Legge 

 Peak, which accordingly is the highest known summit in 

 Tasmania, a satisfactory conclusion to the investigations of 

 the height of Ben Lomond commenced by Col. W. V. 

 Legge in 1906. The agreement between the results by 

 aneroid and by the theodolite is remarkably close, and 

 could not be expected to occur again in similar conditions. 



The claims of Barn Bluff to be higher than its neigh- 

 bor, Cradle Mountain, have still to be tested by survey. 



