160 DISCUSSION ON THE GENERAL REPORT OF SUB-COMM IV-3 
Identical models under very well controlled con- 
ditions were measured by several persons, and 
from certain operators we obtained the results 
which would indicate quite evident distortion; in 
other cases there was no sign of any distortion. 
So it was deduced that it was human error due 
to the physiological elements and also to the 
interpretation, to the concept of the measured 
points. 
That, of course, is only a beginning of a large 
investigation which should be conducted. On 
Tuesday morning we had a session of Com- 
mission I which was an extremely interesting 
and important one. 
The next conclusion was, as I have mention- 
ed already, that instrumental and photographic 
stability seems to be satisfactory and may justify 
using in the future empirically determined cor- 
rections in order to reach what I call the op- 
timum correction in photographic determina- 
tions. 
The next conclusion was that the vertical 
accuracy is higher than often quoted values. We 
must revise slowly the figures concerned with 
accuracy, because in view of this experimental 
work which is very convincing — because, after 
all, we got 38 independent results from different 
countries by different operators with different 
equipment — the results are really very excellent 
and better than the figures which are generally 
assumed. 
Another very important point — and I am 
very grateful to Professor Finsterwalder for 
having pointed this out — is the question of 
quality of graphical presentation. Of course, it 
is a question of decision, how far we like to go 
in graphical presentation of our mapping results. 
We may decide that it is not necessary and too 
expensive to draw beautiful maps. However, the 
maps should be complete, and should be plotted 
in such a way that there should be no doubt 
about the details which are presented. In this 
regard, of course, the quality varies very, very 
widely, and it is one of the difficulties in an- 
alysing the results because there is no method of 
expressing quality of maps in any figures. There- 
fore, all the results which are obtained from 
numerical methods which concern quality and 
time, not quality but time, of mapping and so 
on, must be considered also from the point of 
view that quality has not been included in the 
final evaluation. 
As a last conclusion, it is a statistical result 
which is quite obvious, that anaglyphic types 
of plotters seem to be less precise than parallax 
types of plotting equipment. We had a large 
group of second order instruments of non- 
anaglyphic type, and we had about ten ana- 
glyphic type plotters used. The results seemed 
to corroborate the results of the first interna- 
tional experiments which showed that ana- 
glyphic type plotters are slightly slower in 
operation and less precise. 
I understand that this is a delicate situation. 
Such a statement and such a finding have 
nothing to do with any decision as to what type 
of equipment should be used in operation. As 
long as we know what the performance of 
certain equipment is, users have to decide what 
is the most economical for them. There are, of 
course, other considerations which must also be 
taken into account, but I think it is our task 
to state the figures as they are. 
There, more or less, are the conclusions, and 
perhaps we can now call on somebody to con- 
tribute to the discussion. 
Discussion 
Prof FINSTERWALDER: Ich möchte noch auf 
einige Punkte hinweisen. Es kommt nicht allein 
auf die Güte, auf die Qualität der Auswertung 
an, sondern auch auf die Vollständigkeit, und 
die Richtigkeit der Formen in den Schichtlinien. 
Es ist schade, dass Herr Tewinkel nicht da 
ist, der ja die Untersuchungen durchgeführt hat. 
Ich möchte da auch auf etwas hinweisen, was 
mir wichtig erscheint, dass man den Schicht- 
linienabstand nicht zu eng nehmen darf, weil 
nämlich bei diesem engen Zusammendrängen 
der Schichtlinien dann keine Möglichkeit mehr 
besteht, die Formen der Schichtlinien, diese 
differenzierten Formen richtig zu zeichnen. Und 
dann wollte ich noch auf etwas hinweisen, was 
Herr Blachut leider nicht erwähnt hat. Er hat 
auch eine sehr wertvolle Untersuchung über die 
Vollständigkeit der erreichten Ergebnisse erzielt, 
und da möchte ich nur noch eine kleine Korrek- 
tur oder Ergänzung geben zu der Art und Weise, 
wie das untersucht worden ist. Da darf ich eine 
Zeichnung machen. Wenn wir als Abszisse die 
Zeit und als Ordinate den Vollständigkeitgrad 
in Prozent auftragen, dann hat Herr Blachut 
angenommen, dass der Fortschritt linear mit 
der Zeit geht bis zur Vollständigkeit von hun- 
dert Prozent verläuft. Diese Vollständigkeit sei 
in einer bestimmten Zeit erreicht worden. Da 
muss man nun etwas sagen. Eine Vollständig- 
keit von 100 Prozent kann man bei keiner Aus- 
wertung erreichen. Es wird da irgendwie auf- 
hören, und wir kommen nur bis hierher. Und 
uni 
3