94 Mr. Pogson on the Madras Celestial Survey. 



against each star. Upon revision, by slowly sweeping with 

 the telescope over the zone under examination, with the 

 reticle in the tield of view, each individual position and 

 magnitude is verified, and the magnitude number crossed 

 through horizontally, and no star is ever inked in until 

 thus checked. Omitted stars are at the same time inter- 

 polated differentially, never by estimation, and these again 

 await a similar revision on a subsequent night. Thus, and 

 thus only can I conceive it to be possible to ensure the per- 

 fection of the work ; but by strict adherence to this simple 

 plan, the omission of a star, or an error of position recogniza- 

 ble on the scale of projection employed can only arise from 

 gross negligence ; and such I trust will never be found in 

 any portion of the Madras Southern Survey. 



Publication. — Lastly ; — as regards the time and order of 

 publication of the various charts : — partly owing to the yet 

 unfinished state of the Observatory, the improvements and 

 alterations in which are far from completed although con- 

 siderably advanced — but chiefly from the priority due to 

 the Variable Star Atlas, which it is now hoped speedily to 

 have out of hand, I scarcely venture to expect that the first 

 issue of a Survey Chart can be ready under two years from 

 this time. The repairs and the atlas once completed, the maps 

 will however make rapid progress, and they will be published 

 as finished, regardless of numerical order. Nos. 3, 4, 15, 16, 

 19, 20, 62, 63 and 64 are now in hand, though but little has 

 been done at any of them in the way of actual observation. A 

 complete though necessarily very condensed star-catalogue 

 will accompany each map. The final revision will in no 

 case be entrusted to another, so long as I possess health and 

 energy to accomplish it myself. Numbers 1 to 24 will pro- 

 bably be the laet to appear, as they require by far the great- 

 est amount of labour, both preliminary and throughout their 

 construction ; while their want is in a great measure already 



