324 <A. C. Ramsay on the Glacial origin of certain Lakes 
cataract, and all to whom I have shown them seemed similarly 
impressed : it was not until recently that I learned that they were 
taken with the Harrison globe lens, thus furnishing another con 
vineing argument in my mind of the value of the instrument 
I cannot too’strongly urge their adoption by photographers, and 
am proud of them as originating in America. The shortness of 
their focus adds much to their portability, as the camera is made 
smaller than usual, and amateur field photography with the globe 
lens and dry plates is a pleasure in place of a labor. Its advan 
tages may be summed up in a few words. Short focus, clear 
definition, wide angle of included vision, absolute correctness ¢ 
copy on a plane surface, and tolerably quick work. It takes the 
place entirely of the orthoscopic lens, giving absolute correct 
ness to marginal lines, while the orthoscopic was only approx’ 
imately correct. It fills all the requirements of a lens for land- 
scape and architectural work, and is wanting only in the one 
thing of absolute instantaneity of action. 
Philadelphia, March 10, 1863. 
[We may add to Mr. Seller’s notice of the ‘Globe Lens’ that 
this instrument has been found to reproduce military and other 
maps and plans with a minute fidelity heretofore unattaine®s 
and by their use our Army and Navy are furnished with photo 
graphic copies of manuscript maps and Coast-Survey plans, 1? 
which, as appears from the statements of the officers in charge 
there is no sensible distortion of the right lines, even on Vey 
large plates.— Eps. ] 
Arr. XXXIIL—0On the Glacial origin of certain Lakes in Switeer 
land, the Black Forest, Great Britain, Sweden, North Aw 
and elsewhere; by A. C. Ramsay, F.R.S., President of re 
Geological Society, &c. (Communicated by the Author.) 
Erroneous theories of the transport of Alpine B cee = 
ear 1859, in a series of papers by the members of 
lub, I published a memoir in which I compared the old glacier’ 
of North Wales with those of Switzerland; and in it, am0.5 
other matters, I 0 the glacial origin “ meres d gle 
in the 0/4 6° 
basins now holding lakes, on the watersheds an oe 
cier-valleys of both those countries; and in a later yer 
same memoir, published as a separate book, wit 
zk ie ea these generalizations to many of the la 
ands 
re. ae 
_ In the same work I also expressed an opinion that the blocks 2 
__* From the Quarterly Journal of the Geological Society for August, 186% 
Wales,’ fLeapean 4 Oe Ry Seas 
kes in Sty 
