No. 7.] DECLINATION. 19 
Pl. I—XVII. In the case of every series of observations, I have placed the 
deviations from the lowest value of the day in column D, or in column M, 
as ordinates according to the scale 1°10 mm., so that every millimetre is 
equal to 6’, while the hours are marked as abscisse according to the scale 
1">—10m.m. As the observations were only taken in the daytime, the time- 
scale extends only from 9 a.m. to 9 p.m. 
