Polar Expedition. vi. 
It appears that the great impediment to improvement and 
discovery in this branch of the science of optics has arisen from 
the difficulty of foiling glass to the various forms necessary, in 
lieu of which we have been compelled to use metallic substances. 
These difficulties once removed, a vast field of important dis- 
covery will be opened on the nature and effect of light. -May 
not many of the phenomena that are observed in the air, such 
as halos round the sun, be produced by this principle, the rays 
falling upon a denser medium than air, and thus producing a 
zone of light? &c. 
The further particulars of this important discovery we hope 
to lay before our readers in a future number. 
POLAR EXPEDITION. 
For the following interesting observations on the state of the ice 
in the Arctic Circles, and the probability of our Northern expe- 
dition accomplishing its objects, we are indebted to the intelligent 
captain of one of our Greenland ships recently arrived here: 
“¢ The probability of the ships which have sailed to the North 
attaining one or more of the ends sought, is a subject on which 
much argument has been used, and much difference of opinion 
expressed. On the morning of the Sth June, I was in latitude 
» 79 deg. 40 min. N. about 40 miles distant from the land, reaching 
to the south, along the edge of the ice, and at that time saw both 
ships beating into Magdalen Bay. As early as the 2d May, I 
was in latitude $0 deg. 10 min. N. and had found the country 
remarkably open until 1 approached 78 deg. 40 min. N. Be- 
yond this the ice was more considerable in quantity, and much 
more compact, so as to increase the difficulty of our progress 
further, but not sufficient to preclude our reaching what is called 
the fast ice. Here was presented an obstacle which nothing 
could overcome but a long succession of northerly winds, which 
if occurring, might be expected to separate and force it down. 
In the interval between the 2d May and 4th June, I was chiefly 
in low latitudes, but previous to the 10th was again as far as 79 deg. 
45 min. N. The ice had indeed come down a considerable di- 
stance, but remained equally close and solid, so that 1 am posi- 
tive no rational hope could at that time be entertained of reach- 
ing, or even coming near, the Pole, 
** The other objects of the expedition I have no doubt will be 
fully realized, viz. the ascertaining whether Spitzbergen be an 
island, or joins some other land ; and the investigating the situa- 
tions of the bays, inlets, &c. The ice this season separated very 
early from the land, which circumstance was certainly favour- 
able to the minor, if not particularly so to the major, objects of the 
undertaking. In giving my opinion decidedly against the proba- 
E 4° bility 
