66 Mr H. Blackadder on Unusual Atmospherical Refraction . 
differs in its locality, the structure of the peridium, and its con- 
tents. In the present species the flocci are remarkably abundant 
and silky, and eventually conceal the peridia altogether, when 
the whole bears the strongest resemblance to a Sporotrichum. 
It commences in small tufts two or three lines broad, with fine 
creeping adpressed byssoid margins, which at length unite, and 
form a continuous line of an inch or more in length, and vary- 
ing in breadth according to the part on which it grows. 
PI. I. Fig. 1. Plant natural size. 2..Sporidia and filaments 
enlarged. 3. Do. highly magnified. 4. One of the Spori- 
dia bursting. 
Wharton Place, ^ 
November 1. 1824. f 
Art. V. — On Unusual Atmospherical Refraction. By Hen- 
ry Home Blackadder, Esq. Surgeon, med. staff h. p. 
(With a Plate.) 
Pip 
-1- HOSE who may have witnessed, in this country, and in the 
afternoon and evening, the phenomenon termed Mirage , if their 
attention was not altogether absorbed by the beauty and inte- 
resting nature of the spectacle, must have remarked the coinci- 
dence of the state of the atmosphere with that in which dew or 
hoar-frost is most likely to be formed, or in which their imme- 
diate cause is most likely to be in active operation. In advert- 
ing to this subject, one can hardly avoid noticing the remarkable 
inattention of not a few to what is passing under their immediate 
view, while they eagerly search after that which is distant, and 
far removed from the sphere of their contemplation. For what 
purpose look to the frozen polar and burning equatorial re- 
gions for descriptions of phenomena that may be seen at home 
in equal beauty and perfection, and almost without moving from 
their door or window ? Is nothing interesting but what is dis- 
tant ? Is nothing valuable but what infers difficulty and exer- 
tion ? The mirage is not an every day’s occurrence in this nor 
in any other part of the world, but it may be witnessed often 
enough in this immediate neighbourhood, to satisfy the most 
curious inquirer. 
