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[FORM No. 18.] 



TRANSIT OF VENUS, 1874. APPENDIX. 



[PAGE 



BRITISH EXPEDITION FOR OBSERVATION OF THE TRANSIT OF 



VENUS, 1874. 



COMPUTATION OP NORMAL-CENTRIC ELEMENTS. 



(The surface of a concentric sphere being supposed to touch the equator, and a line normal to 

 the equatoreal plane being drawn through the observing station to the surface of the sphere ; its 

 intersection with the surface of the sphere is the " corresponding point ;" and the latitude, on the 

 sphere, of that point is the " corresponding latitude." 



The normal to the spheroidal surface at the observing station, being produced to intersection 

 with the earth's axis, is the " Normal-centric radius ;" the place of that intersection is the " Normal 

 Center," always in the hemisphere opposite to the hemisphere of the station ; the distance of that 

 intersection from the Earth's Center, measured along the earth's axis, is the " Axial Distance of 

 Normal Center.") 



NOTE. Angles are to be taken to the nearest 10". 

 Logarithms to 5 decimal places. 



Computer's signature. 



