1832] Progress of Indian Maritime Surveys. 333 



experiments the time can be taken to a tenth of a second, the distance 

 of the two vessels is obtained by this process to within at least 50 or 

 60 yards. 



The angles subtended by the different points on shore, are taken 

 always with the sextant, and the azimuth compass is only resorted to m 

 order to lay down the true meridian. The practice of taking points 

 by bearings of the compass, though common with many nautical sur- 

 veyors of repute, is one that admits, comparatively with the sextant, 

 of very little accuracy. The theodolite cannot be used on board ship. 



Frequent observations for latitude and longitude, made both on shore 

 and on ship-board, and as well from morning as from evening sights, 

 afford further means of insuring accuracy ; and it has been stated, that 

 upon the result of the survey made of the coast and archipelago of 

 Mergui and Tenasserim, extending through a space of eight degrees of 

 latitude, and of one or one and a half of longitude, and comprising 

 upwards of 600 islands entered in the chart ; the difference in position 

 of any two intermediate objects found trigonometrically, barely ex- 

 ceeded, when tested by careful observations for latitude, one quarter 

 of a mile : — more than this cannot be desired for any purpose within 

 the objects of a Marine Survey. 



It has been usual for the Government, upon receiving each chart as 

 it is completed, to strike off a few copies by lithography, and to send 

 the originals to England, where they are engraved by the Court of 

 Directors, and we presume, made accessible to the public. We have 

 heard occasional complaint of difficulty in procuring copies, but whe- 

 ther that difficulty refers to their not being furnished from the Go- 

 vernment offices in India, or to disappointment at not being able 

 to procure them here to purchase, we confess that we do not thorough- 

 ly understand. The later Charts of Captain Ross, and in particular the 

 very interesting survey of the Mergui archipelago and Tenasserim coast, 

 are well deserving of the attention of the Geographical Society in 

 England, from the additions they afford to the geographical informa- 

 tion possessed of those countries ; and we hope to see them noticed 

 with due acknowledgments by that Society. Did we possess the same 

 facility of neat engraving, that publishers in England have at command, 

 we should have thought it our duty to annex to this article, a sketch of 

 the whole of this coast and of its islands, as now laid down, compared 

 with the same as given in the latest previous Charts, in order that the 

 extent of the improvement effected might be duly appreciated. The 

 backwardness of India in this branch of art compels us to leave this 

 to be done by others. 



