597 



has furnished, on the inadequacy of the vertical circles of the instru- 

 ments employed by Colonel Lambton, on the want of attention to 

 atmospheric circumstances, and on the want of simultaneity in re- 

 ciprocal observations (all which considerations have been carefully 

 kept in view in Sir George Everest's and Sir A. Waugh's observa- 

 tions), the Committee recommend that Colonel Lambton's determi- 

 nations of height of base be rejected, and those of Sir George Everest 

 and Sir A. Waugh be adopted ; and that the resulting corrections 

 be made to the estimated lengths of Meridian Arcs, as far as, in the 

 judgment of the Officer revising this work, It is now possible to 

 do it. 



5. The reductions of astronomical observations for celestial am- 

 plitude of arcs and absolute determination of latitude admit of easy 

 examination; and the Committee recommend that they be thoroughly 

 verified. The Committee recommend that the original numbers of 

 these observations, as well as those of celestial azimuths, be verified 

 by collation with any manuscripts of the Survey which may now be 

 preserved in England. 



6. The reduction of the Latitude-observations was corrected 

 several years ago by Bessel. The Committee are of opinion that 

 additional accuracy can now be given to these corrections. First, 

 the proper motions of the stars are now better known than they 

 were in Bessel's time. Secondly, the value of the coefficient of 

 Nutation used by Bessel is now universally abandoned by astro- 

 nomers. The alteration made in the result by the use of corrected 

 values of these elements would probably be small ; but, remarking 

 that they can be introduced with great facility, the Committee re- 

 commend that the corrections be made. 



7. The Committee have had personal experience of the great in- 

 convenience caused by the dispersion of Colonel Lambton's accounts 

 of the survey-operations through numerous volumes of the Asiatic 

 Eesearches; and viewing the limited circulation of that work in 

 continental libraries, they are inclined to believe that very few men 

 of science have it in their power to form a correct judgment as to 

 the value of Colonel Lambton's great work. The Committee there- 

 fore recommend that, when the verifications and corrections which 

 they have particularized shall have been made, the whole be pub- 

 lished in one volume, in a form as nearly similar as circumstances 



