Survey of Northeast Greenland. 463 
a photo from 1913 of the quite analogous phenomenon from the 
marginal zone of the inland ice). 
In Meteorol. Terminbeob. am Danmarks Havn, Medd. om Grønl. 
XLII, WEGENER has published a great number of sketches and some 
photos of mirages. By going ihrough the latter one will quickly 
find a series of upward mirages, which do not accord with the 
above description (see for instance the sketches on pp. 241, 288, 292, 
Plates XI and XII and others). The inversion of temperature con- 
ditioning these mirages at Danmarks Havn lies at an altitude of 500 
to 600 m. In Drachen- und Fesselballonaufstiege, Medd. om Grønl. 
XLII, pp. 62—64 WEGENER quite briefly mentions the meteorological 
conditions pertaining to this kind of upward mirages. In particular 
I shall draw attention to the curves of temperature delineated on 
р. 65, which show that the rise in temperature may take place in a 
series of small jumps, corresponding to the same number of bounding 
surfaces, each of which may cause a reflection. These upward 
mirages are materially different in character from the above. The 
‘column structure is only slightly pronounced, and is perhaps lacking 
altogether; the reflected image is not limited to a narrow streak, 
but lifts itself high into the air; the boundary line at the top is, as 
a rule, jagged and very uneven in height; the movement in the 
images is quieter, which shows that the waves of the bounding sur- 
faces in this place are of a somewhat different kind. If one finds 
oneself on a mountain and quite close under the reflecting surface, 
the images, owing to one’s own movement up and down, may change 
both quickly and strikingly, as will appear from the description 
below of a reflection in Dronning Louises Land. 
It is by no means an uncommon phenomenon in the autumn 
simultaneously to come across upward and downward mirages. 
In order to give a somewhat more complete idea of the im- 
pression which mirages may produce upon the observer, I will to con- 
clude quote the description given of two particular cases from the 
voyage across Greenland in 1912—13. 
Borgfjorden (the ice fjord of Storstrømmen) Sept. 20th 1912. 
— — — Homewards we went, with empty sledges and in our 
old tracks. There was time to enjoy the beautiful clear and frosty 
September evening. The shining, white fresh snow, wreathing the 
upper edge of the icebergs, enhanced their blue and _ yellow-red 
colours. The generally so massive and imperturbable ice colosses 
became light and airy. They stretched in a downward direction 
and seemed to rock gently on a crystal lake in the snow-covered 
plain of the fjord. 
It was the downward or the “autumn” mirage in the warm 
XLVI. 30 
