ISOSTASY 569 
difference is .499, whereas the factor itself can have a total range 
of only 1.000. 
2. That for other various assumed values of M, with the same 
value of f/x, his factors always differ largely from Hayford’s for 
some rings. If M=.9, for example, the maximum difference 
occurs on ring 14 and is .496. 
3. That to secure a close agreement in the computed deflections 
from two sets of reduction factors used at various stations there 
must be a close agreement of the factors for the separate rings, 
not simply an agreement in the average values of the two sets of 
factors, since the computed deflections for the various rings at 
a given station differ greatly." At Point Arena, for example, 
the topographic deflections for various rings vary from + or for 
ring 24 to 10’10 for ring 6, and at Uncompahgre from +2735 
for ring 13 to —5’o7 for ring 1. These topographic deflections 
for separate rings are the quantities which are multiplied by the 
reduction factors to obtain the computed deflections. Evidently at 
Uncompahgre a decrease in the reduction factor in ring 13 will not 
be partly neutralized in effect by an increase of the factor for ring 1, 
but instead the two effects will be of the same algebraic sign, 
since the topographic deflections for these rings happen to be of 
opposite signs. 
4. That the proposed Lewis factors corresponding to incom- 
plete compensation are always greater than the Hayford factors 
for the extreme outer rings (distant topography), and less than the 
Hayford factors in the inner rings corresponding to topography at 
a moderate distance. This gives a clue to the reason for the fact 
that at some stations it requires a decrease in assumed complete- 
ness and at other stations an increase to counteract an assumed 
decrease in depth of compensation. In this connection it is impor- 
tant to note that the 733 stations used in the computation being 
criticized are in a great variety of locations with reference to near 
and distant topography. 
5. That following the clue suggested in (4), it becomes evident 
that there is no fixed relation between the effect upon the compu- 
t Consult pp. 26-33 of The Figure of the Earth and Isostasy. 
