12 REPORTS ON THE STATE OF SCIENCE.—1917, 
As regards seismographs other than G, the corrections to G appear 
to be sensibly constant at any rate to a good first approximation. They 
are assigned by the 1913 and 1914 results as follows, omitting some of 
which observations are scanty :— ‘ 
TaB_e III. 
Corrections to G from other Seismographs. 
Ty Correction No. Correction No. | Correction 
| ype to P Observatns. | tos Observatns.| to S-P 
s. s. 8. 
Alfani + 38 17 SS 17 —7'0 
Bosch + 18 27 Kee) 22 —4:7 
Bifilar + 1:3 19 + 9-4 16 +81 
| Bosch-Omori + 19 18 | +40 | 39 +21 
| Cartuja . 33 36 | + 68 igo: ee 
| Heidelberg .| +23 | 27 +43 =| 34 +2°0 
Hemipure: oy Ol 2 ee eae 39 + 1:2 32 —2°9 
| Sites ater cs (5 rood yh oll gem eae ed +17-0 10 432 
Mainka . , : ol 20a), 2e — 02 112 +0°5 
| Omori . : g : + 6°5 95 + 9-8 57 +3°3 . 
Omori-Alfani moter 2 4+ 35 10 44:2 
| Omori-Ewing — 2°6 29 leks 17 —8'9 
Riverview +16 | 25 + 7:2 29 +56 
| Stiattesi — 06 | 53 — 16 65 —1°0 
Vincentini +,0:6 | 48 -- 2°6 33 -++2:0 
| Wiechert ty =e 3:3 720 +. 5°7 493 4+2°4 
It will be seen that the corrections to the tables for G instruments, 
and the differences between one instrument and another, are such as to 
involve sensible corrections to the determinations of epicentre; and the 
next step is clearly a revision of the epicentres before forming definitive 
corrections to tables. This revision, and the analysis of the errors beyond 
A=90°, must be reserved for another Report. 
Distribution of Epicentres. 
The epicentres lor 1913 and 1914 were entered on a map and were 
found to lie near two great circles cutting at right angles. The first of 
these has its pole just east of Malta, in 
longitude 17° E., latitude 35° N., 
which is the centre of a very good ‘land-hemisphere,’ the boundary of 
which skirts the KE. coast of Asia; it crosses both the Americas, and leaves 
Australia and several of the large islands in the ‘ water-hemisphere.’ 
The other has its pole in 
longitude 236° EB. = 124° W.; lat. 48° N. 
A third circle cutting both these at right angles does not seem to be active ; 
its pole is at 122°H.; 20° N. 
In view of the proposed revision of epicentres (which, however, is 
not likely to modify these figures seriously), the reproduction of the 
maps is held over for the present, 
