1864.] 



Iteport of the Great Trigonometrical Survey. 



301 



last season by Mr. Shelverton. It is single throughout. The recess 

 computations will be completed by 1st October, when the party will 

 be transferred to the meridian of 80°, to execute the required triangu- 

 lation between Jubbulpore and Madras. During the past Field Season 

 the triangulation extended over a distance of 112 miles, covering an area 

 of 1,366 square miles. A very creditable amount of secondary tri- 

 angulation was also executed. The total cost of the Series, up to 1st 

 October, the date of its completion, will be about Eupees 80,743 ; 

 the total area covered by the trangulation is 8,142 square miles, thus 

 giving a rate of Rupees 9-14-8, or nearly 20 shillings per mile. 



The Bombay Party, under the superintendence of Captain Haig, 

 Royal (Bombay) Engineers, having completed the triangulation 

 in Northern Bombay, was deputed to execute a series of triangles to 

 the south of the parallel of Bombay, on the meridian of Mangalore. 

 While the preliminary operations and selection of stations were pro- 

 ceeding, Captain Haig marched to the origin of the Bombay Longi- 

 tudinal Series, with a view to making this Series double throughout, 

 by adding flank stations, so as to form polygons in parts where there 

 were only single triangles. On reaching the ground, it was found that 

 the ends of the Beder Base Line were, fortunately, in good preservation. 

 Three of the advanced stations had, however, been completely destroy- 

 ed. Captain Haig judiciously determined to triangulate the Series 

 anew, as far west as the Mangalore meridian. The revision having 

 been executed with a much superior instrument to that employed in 

 the original triangulation, the value of this portion of the Bombay 

 Longitudinal Series is very greatly enhanced. 



Having completed this revision, Captain Haig was proceeding 

 with the principal triangulation on the meridian of Mangalore, when 

 an untoward accident brought his operations to an abrupt termination. 

 The large Theodolite was set up for observation on the tower station 

 of Palwan, when, without any previous warning, the tower gave way 

 on one side, causing the fall of the instrument and observatory tent, 

 whereby the instrument was so seriously injured that it is incapable 

 of being again used, until it has been repaired by the makers in 

 England. Fortunately, the horizontal circle, the most valuable portion, 

 appears to have escaped injury, but the vertical circle was destroyed, 

 and the injuries are such that the instrument cannot be repaired in 

 this country. Captain Haig convened a Court of Enquiry to report 



