78 The Rev. H. Lloyd on the Results of Observations made at the 



Table II. Coefficients of the EdnATiON of the Diurnal Curve of Declination. 



6. From the inspection of the nxunbers of this Table, -we draw two impor- 

 tant conclusions : 



I. The values of the four latter coefficients, Bt, A^, B^, Ag, being small, 

 all the terms of the series beyond the eighth may be neglected as incon- 

 siderable. From this it follows, that eight observations, made at equal intervals, 

 are sufficient to determine the course of the diurnal variation. 



u. On comparison of the values of A and B for the separate months, it ap- 

 pears that there is a general resemblance in the course of the diurnal variation 

 in the six months from April to September inclusive, as well as in the sis 

 months from October to March inclusive ; and that thus the curves for the 

 separate montlis distribute themselves naturally into two groups, in one of 

 which the sun is to the north, and in the other to the south of the Equator.* 



Hence, if we confine our attention to the three latter rows of the pre- 

 ceding Table, which give the values of the coefficients for the summer half- 



* This fact appears likewise upon an examination of the immediate results of observation, as 

 given in Table I. ; and still more readily by the inspection of the curves in which these changes 

 are graphically represented.— (See Plates I. and II.) 



