Decl. at Greenwich mean noon, March 3rd.. 1'' 7 02' 00" 



Correction, 57". 37 3.7 - - - 03' 32" 



True Declination - - S' 28" 

 Co-declination, (90 d) SP - 



Apparent Altitude 



Refraction Correction for 2'j hours, (see page 164) 01' 16" 



True Altitude - - - 33 31' 14" 



Co- Altitude, (90 h) SX 



Lei it be assumed that the latitude is 41 28' 48" 



Then the co-latitude, (90 1) ZP - 48 31' 12" 



Co-dec 96 58' 28" 



Co alt 56 28' 46" ac Log sin 0.0789966 



Co-lat 4S 31' 12" acLogstn -0.1254098 



The Ross Meridiograph * 



The expert investigation! of Mr. Ross into the mathematics of 

 direct meridian determination has developed a circular slide rule of 

 logarithmic scales by which the sun's azimuth may be rapidly 

 calculated in the field. 



The declination, the latitude and the sun's altitude are to be 

 established by any of the well known processes. These values are 

 laid off on the proper scales, and the azimuth is to be read off directly 

 by inspection. 



It consists of two circular celluloid discs and a reading arm 

 rotating about a common center. On the discs are graduated eight 

 separate logarithmic scales of altitude, latitude, declination and 



Consult also Eng. A- M4; Colliery Engineer, Jun, 



& Cont. July 15. 1914. eU. 



