322 TRANSIT OP VENUS, 1874. EGYPT. 



errors of the transit, as this instrument came from Mr. Simms' factory only 

 just in time to be packed up before leaving Greenwich ; consequently all 

 instrumental corrections had to be determined before a single observation 

 could be reduced. I soon discovered that the micrometer-screw was decidedly 

 drunken, and was compelled to abandon its use. This entailed very serious 

 loss of time every night, and compelled me to trust to observing the pole star 

 in both positions of the instrument over the fixed wires for collimation, as 

 well as for azimuth errors. 



Having no covering for the instrument, I carried it into my room and put 

 it in its box each night. 



On November 24 I packed the instruments and returned to Cairo. 



S. HUNTER. 

 (Continued on page 333.) 



MERIDIONAL OBSERVATIONS at ALEXANDRIA. 



Mr. Hunter's observations for local time were continuous from 1874, 

 October 30 to November 23 ; but have special value only on those nights 

 when signals were exchanged with Mokattam. 



The Level Error was determined by a striding spirit-level graduated from 

 the center outwards in the old way ; 40 divisions were equivalent to one 

 minute of arc. 



After his return to England Mr. Hunter carefully determined the Pivot 

 Correction to be 0"'88, positive with the Micrometer Head East. 



The Equatorial Intervals of the nine vertical wires were determined from 

 numerous transits of circumpolar stars over the entire set. The correction 

 to reduce the mean of the wires to the center wire was 1"'58, positive with 

 Micrometer "West. 



The Collimation Error of the center wire was determined by observations 

 of polar stars with reversed positions of the Transit axis. 



The Azimuth Error has been obtained, and the reductions effected in the 

 same manner as at other stations. 



The Diurnal Aberration is taken account of as a correction to the Longitude. 



In adopting the Error of the observing Chronometer (Loseby 102) equal 

 weight has been given to the observations in each of the reversed positions 

 of the transit instrument, irrespective of the number of stars observed. 



It was Mr. Hunter's custom to compare the two chronometers (by coinci- 



