114. L. A. Bauer— Variation of Terrestrial Magnetism. 
hence, largest recorded change is 6°°0. Similarly, we find 
for the same point the largest change in inclination to be 3°°5 
It must not be understood that these are the maximum decli- 
nation and inclination changes during the interval 1780-1885. 
To have obtained these quantities it would have been necessary 
to establish interpolation formule or resort to graphical meth- 
ods. To get results expeditiously I simply took the maximum 
and minimum quantities as they stood in my original tables; as 
only the mean results exhibited at the bottom were employed, 
this rapid method was sufficiently accurate. 
It will be seen that the second last column is left blank 
except for the points 280° and 300° K. The reason of this is, 
that I could not scale safely the inclinations for this latitude 
on Hansteen’s isoclinic chart of 1780. In consequence, the 
largest change in inclination during the interval 1780 to 1885 
could not be determined for this latitude. It might have been 
obtained for the epoch 1830-1885, but these quantities would 
not have been strictly comparable with the others: 
The 9th column headed “ Mean” gives the mean largest 
change in declination from 1780-1885 at every meridian 20° 
apart, as determined from the seven symmetrically situated 
parallels. The last column gives the same quantities for the 
inclination. Here, however, in order not to disturb the sym- 
metry only the five parallels +40°, +20°, 0, —20° and —40° 
could be utilized. Approximately then, we may regard the 
quantities given in these two columns as applying to points 
along the equator 20° distant in longitude. 
The first horizontal row of figures gives as indicated the 
mean of the 18 quantities in each column. The figure 6-4 as 
given in the final column is the mean of the preceding five 
quantities of the row or of the 18 in the column above. The 
bottom row gives the difference or range between the largest 
and the smallest value in each column. 
From this table a number of conclusions can be drawn. I 
shall mention, for the present, only two, preferring to draw 
attention to the others in their proper places. 
V. The minimum average secular change in declination along 
a parallel of latitude from 1780 to 1885 occurred near 
the equator, the values generally increasing upon leaving 
the equator. 
VI. The maximum average secular change in inclination 
along a parallel of latitude from 1780 to 1885 occurred 
near the equator, the values generally diminishing upon 
Jeaving the equator. 
These two laws* are precisely analogous to Nos. III and IV. 
* It will be noticed that the bottom row of figures giving the “range” exhibit 
practically the same results. 
