554 PROCEEDINGS OF SECTION E. 



Strang way's Springs Trigonometrical Station, gives 29° 12' 05" for 

 that place ; while, by calculation from Kingoonya, situated 120 miles 

 south, it is 29° 12' 03". Continuing northward. Mount Margaret works 

 out 28° 29' 15", and Mount Alberga, in the Musgrave Ranges, 26° 59' 

 06", specially determined at different times by Messrs. E. B. Jones 

 and J. Carruthers as 26° 59' 04|-" (which is l|secs. less than the calcu- 

 lated value). Carrying the computed value of Mount Margaret north- 

 eastward to Cowarie and thence northward to the south-west corner 

 of Queensland a perfect close is obtained on the 26th parallel. Obser- 

 vations for fixing the 26th parallel of latitude, forming part of Queens- 

 land boundary, were conducted by Mr. Aug. Poeppel, with a 6in. transit 

 theodolite and two sextants. Three observers took part in the obser- 

 vations, which were numerous and conclusive. The line was marked 

 in short chords westward through three degrees of longitude, the utmost 

 care being taken to preserve its true curve. 



During the survey northward of the boundary line between the 

 Northern Territory and Queensland, 1883-86, some special sets of 

 observations were taken, showing a remarkably close atjreeraent be- 

 tween the measured and observed intervals of latitude. Notably at 

 the Woodroffe, 311 miles 4,718 links, where the mean of 100 observa- 

 tions of meridian transit of stars gave 28° 21' 06" against 28° 21' 05"-9 

 calculated. When opposite the Herbert River, a tie was made with the 

 junction pile, 20 miles 1,526 links west and the latitude 20° 36' 09"-07, 

 observed by Mr. Winnecke five years previously, was now found by 

 chainage from the 26th parallel to be 20° 36' 09". Crossing the high 

 land in the region of Nicholson Eiver the chainage showed some slight 

 discrepancy with the observed latitude (1" to 2"). When the Gulf of 

 Carpentaria was reached the observed latitude— 16° 30' 25"-84 — was 

 3" lower than that given by chainage from the 26th parallel through a 

 distance of 650 miles 5,700 links. 



During recent years the latitude of Mount Gambier Trigono- 

 metrical Station has been calculated from Adelaide, partly by triangu- 

 lation and partly by chainage of hundred boundary lines' compared 

 with data of the railway survey. The resulting latitude is 37° 50' 30" 

 against 37° 50' 32" observed by the late Mr. Allen, of the Victorian 

 Geodetic Survey. 



CLOSING REMARKS. 



Considerable discrepancies frequently occur between observed 

 and calculated latitudes (of which no mention has been made here), 

 due partly to local disturbances of the spirit-level from gravitational 

 causes, and partly to inexperience on the part of the observer. 



The answer to a question sometimes asked as to whether any 

 noticeable deflection of the plumb-line has been induced by the sub- 

 sidence of the Lake Eyre basin in the interior, or by the elevation of 

 mountain masses elsewhere in South Australia, is bound up Avith this 

 subject ; and it is hoped that the present paper mri,y help at some 

 future time in the solution of an interesting problem. 



