NATURAL HISTORY MISCELLANY. 185 
both sides. Explorations carried on in the Mediterranean, the 
Red Sea, and the Indian Ocean, showed similar uniformity in the 
level of the sea bottom; and the general conclusions arrived at 
by Capt. Osborn were, that in the deep sea there is an absence of 
bare rock, and that there are no rough ridges, cations or abrupt 
chasms; moreover, that the bed of the deep sea is not affected 
by currents or streams, even by those of such magnitude as the 
Gulf Stream; but that it rather resembles the prairies or pampas 
of the American continent, and is everywhere covered with a 
sort of ooze or mud, the débris of the lower forms of organic life. 
Corossar Fossi Sra-WrEep.—From the microscopic examina- 
tion of the structure of specimens of the fossil trunks described 
under the name of Prototaxites Logani, and which Principal Daw- 
son affirmed in his Bakerian lecture before the Royal Society, to 
be the oldest known instance of Coniferous wood, Mr. Carruthers 
has discovered that they are really the stems of huge Algæ, be- 
longing to at least more than one genus. They are very gigantic 
when contrasted with the ordinary Alge of our existing seas, 
nevertheless some approach to them in size is made in the huge 
and tree-like Lessonias which Dr. Hooker found in the Antarctic 
seas, and which have stems about twenty feet high, and with a 
diameter so great that they have been collected by mariners in 
these regions for fuel, under the belief that they were drift-wood. 
They are as thick as a man’s thigh. — The Academy. 
MICROSCOPY. 
IMPROVEMENTS IN THE LENSES OF MicroscorEs.— For some time, 
people in England have been content to let the improvement of 
the optical powers of the microscope remain entirely in the hands 
of the makers, believing, apparently, that Mr. Lister had effected 
all in his suggestions and improvements that could be desired. 
Dr. Royston Pigott, an able mathematician, formerly fellow of St. 
Peter’s College, Cambridge, and a Doctor of Medicine of that 
niversity, was not, however, inclined to look at the matter in 
this way, and for many years has been working and experimenting 
with a view, first, to test the accuracy of our best object-glasses, 
and, secondly, to suggest means for their improvement. It should 
be remembered that Oberhauser, Nachet, and especially Hart- 
