366 MORTEN P. PORSILD. 
light to penetrate, and the resulting figures must be corrected (raised) 
to allow of comparison with those obtained with paper of coefficient 
0:126. The amount of this correction is about one-sixth, i. e. if an 
actinometer number a obtained with paper 0'145 is to be correlated 
with the figures obtained with paper of coefficient 0:126 then: — 
в: — b or conversely: — 
b — i = A: 
STEENSTRUP has also mentioned, in this paper, some experiments 
made in Greenland, at Egedesminde (68° 42' М. lat... These have 
been made with paper 0'126 and extend over about nine months 
but were carried out on a different plan, the investigations having 
been made only once a week. Consequently, from this series of 
investigations, no results suitable for comparison can be formulated, 
and so it will not be considered in what follows. 
The significance of the Actinometer numbers. Relative intensities. 
From Pryrz’s investigations we know that the actinometer 
numbers cannot approximately represent the relative intensity-values. 
On comparing two intensities, I, and I, obtained with the same 
apparatus, the following relation is found: — 
Г = р", where р denotes the absorption-coefficient of the 
2 
tracing-paper (consequently in the case in question 0'126), and п 
denotes the difference of the actinometer numbers. To save the 
reader the trouble of calculating the value of the numbers which 
Table II. The Differences of the Actinometer Numbers. 
(Corrected for tracing-paper 0'126). 
о 2 3 21 VOUS 6 1. |) 8 RE 
De 10| 11 13) 151 ‘17  »0| 23 пора ЕЙ 
MER 38 | 44 50| ss 66| 75 se oo ae 
are 14.8 | 169| ı94| 22.2 | 254 | 99.0 | 33.2 | 379 | 43.5 | 49.7 
SOV VE 56-9 | 651| 745 882 | 97-5 | 101-5 | 127.6 | 146-1 | 167-1 | 191-2 
по 218.8 | 250.0 | 286-4 327-7 | 375-0 | 429-0 | 490-9 | 561.7 | 642-7 | 735.4 
EN. 841-4 | 962-7 1102 1260 | 1442 | 1650 | 1888 | 2160 | 2472 | 2828 
60... | 3236 | 3702 | 4236 | 4848 | 5546 | 6346 | 7261 | 8308 | 9506 | 10880 
о. 12540 14240 16290 18640 21330 24410 27920 | 31960 | 36560 | 41450 
1 I have to thank Professor Pryrz for deducing the correction-formula 
a 105 (1 — 0. 126) 585 6 
ь— 1081 —0-145) — 680 mur 
