1877.] 



645 



rPrazer. 



These would be as follows : 

 = — 7.49+ 16 X— 736.2 y+ 63832 z— 5792927 u 



Orrr + 573.26— 736.2 x+ 63832 y + 5792927 z— 562891700 u 

 = — 79077 + 63832 x— 5792927 y + 562891700 z— 56610893400 u 

 =+8782402—5792927 x— 562891700 y — 56610893300 z+583 1932000000 u 

 To facilitate reduction Mr. Schott assumes x =: X, y ^ Y : 10^ z ^ Z : 10*, 

 u = U : 10^ Dividing the first equation by 10", the second by 10'^ the 

 third by 10*, and the fourth by 10^ he obtains the modified normal equa 

 tions. 



' 7.3620 

 6.3832 

 5.7929 

 5.6289 



+ 



+ 



+ 



+ 



16.0000 

 7.3620 

 6.3832 

 5.7929 



X 

 X 

 X 

 X 



+ 



+ 



7.4900 

 5.7326 



7.9077 



8.7824 



Their solution gives 



X — + 0.239 hence 



Y = + 8.543 

 Z = + 15.055 

 U = + 5.100 

 and the formula for the declination becomes 



D =r + 7».439 + 0.08543 ft — 1830) + 0.0015055 (t — 1830)'-* + 

 0.000005100 (t — 1830)3. 



A Table of Compariso7is of the Observed and Computed Declinntions at 



Providence here follows : 



r=:0.674\ 1 = ± 00.085= ± 5'.1 



"« — "•"'■' ^n — 4 

 Mr. Schott proceeds to the establishment of formulae expressing the sec 



♦ A misprint makes this 1720 in Appendix No. 48, Coast Survey Report for 18.5o 



pnoc. ameb. philos. soc. xvi. 99. 4c 



