250 I. Р. Koch. 
son is that the computations are performed according to the same 
presumptions as regard the refraction. 
SABINE used the refraction tables of THomas Young in the Nautical 
Almanac for 1822, whereas BORGEN and COPELAND used BESSEL’s 
refraction tables, though they have multiplied the Besslian refraction 
by 0.952"). A re-computation of the refraction of SABINE’s observations 
according to BORGEN and COPELAND’s manner of proceeding, gives the 
following results: 
Sabines computation | Re-computation 
а ;=| Refr. | Få 
Date | Apparent | .= 2| & 8 Si ee , | Rema 
1893 | a må wos | ER М.А. | o Germ.- Ф | 
2: zenitdist. Sp: | = Е 1822 | en | 
3 | SE KØ Al | HS ØER EIN Ds | 09911917 | Sextant and artificial 
21. Aug... |62 12'32” | 29.90 | 39 [151 7 74°32'18".4 |1’47”.0 | 74932'13”.7 horizon 
22. — .. | 62°32'24” | 29:95 | 39  1'53”.5 | 74°32'16”.6 | 1'48".7 | 749321178 || Hele pe 
23. — .. | 62°53'30” 29.907 37.5 | 1’55”.3 | 74°32’20”.0 | 1:50”.4 | 14°39/15" 1. || _ horizon 
25. — .. |63°33'58" | 29.72 | 38 |1'57”.8| 74°32'19".9 | 1'52".9 | 14°32'15”.0 N Repeating Gisele 
26. — 63°54’56” | 29.74 Frere.) 584! 74°32/17".9 153"3 | 74°32/12".8 |] 
Mean... | 74°32/18".6 | 
| 74°38213".7 | 
According to this SABINE's Observatory should thus be situated 
3” more southerly than the Observatory in Germania Harbour, in 
which manner it would, judging by the course of the coastline on 
PAYER's map, lie in the meridian 18°50’00” west of Greenwich, and 
so complete harmony would have been established between SABINE’S 
determination of longitude and that ofthe Germaniaexpedition, while, on 
the other hand, there would undoubtedly arise a serious 
discrepancy as compared with CLAVERINGS map. 
There can be no doubt that BORGEN and COPELAND have per- 
formed the same re-computation of SABINE’s observations as shown 
above. Such complete agreement between their determination of 
longitude and that of SABINE would have been a great triumph for 
them. Astronomers by profession?) they could not help seeing the 
importance of the various ways of computing the refraction, so much 
the less as they had themselves worked on the problem of refraction, 
and on the basis of their own observations had taken the opportunity 
1) As to fuller particulars of this, see under “Astronomical Refraction”, pp. 136— 146. 
?) BORGEN, who had studied astronomy and geodesy in Copenhagen, Kiel and 
Göttingen, was in 1866 appointed assistant at the Observatory of Göttingen. He 
died a director of the Observatory of Wilhelmshaven. CoPELAND, who had re- 
ceived his scientific education in England, in 1865—1867 studied astronomy in 
Göttingen, and afterwards became an assistant at the Observatory in that town. 
He died a director of the Edinburgh Observatory. 
