DR. RANKEN’S INVENTION. 
459 
In many cases there are no appreciable dis- 
tinctions. 
The species are distinguished by the form, 
and still more surely by the number oi septa 
or transverse lines which divide their small 
body ; and M. Ehrenberg, who has been able 
to count them by tlie microscope, has observ. 
ed the same number of these divisions in liv- 
ing and in fossil species- 
They are the tripolis of Bilin in Bohemia, 
of Santa-Fiora in Tuscany, and of other pla- 
ces which I do not lemeraber with certainty* 
(of the Isle of France and of Francisbad near 
Eger, if I am not mistaken,) which have given 
occasion to these curious observations. I’he 
slimy iron ore of marshes is almost wholly 
composed of Gaillonella ferruginea. 
The greater part of these species are lacus- 
trine, but there are also some marine, parti- 
cularly in the tripoli of the Isle of France.— 
Vlnstitut, No. \66.—lhid. 
BRITISH ASSOCIATION FOR THE 
ADVANCEMENT OF SCIENCE. 
The next Meeting will be held at Bristol 
during the week commencing on Monday, 
August, 22nd ; the Members of the General 
Committee will assemble on the preceding 
Saturday. — Ibid. 
THE INDIA REVIEW. 
Calcutta : January 15, 1837- 
LORD AUCKLAND’S SCIENTIFIC 
PARTY. 
Tuesday 'Evening., Zrd January, 1837. 
We rejoice to see our prediction, regard- 
ing the ulterior good to be derived from the 
instructive and interesting entertainments 
at the Government House, realized. 
The ingenuity of talented men has been 
in active exercise, and discoveries have been 
displayed, which will tend to the most im- 
portant results. Although we cannot con- 
cede to Dr. O’Shaughnessy the merit of hav- 
ing discovered the working machine for pro- 
ducing moving power by the application of 
electro-magnetic influence, yet we must ac- 
knowledge that his contrivance of another 
machine, the model of which was exhibited 
at the Government House, and is described in 
our present number, does him great credit 
for ingenuity, perseverance, and zeal, and 
will add to that professional renown for pro- 
mising talents which he has so Justly attain- 
ed. In addition to the foregoing on the 
present occasion. Dr. Ranken, officiating 
secretary to the Medical Board, — a gentle- 
man already distinguished for his mechanical 
genius by his invention of the thermantidote, 
an engine by which ordinary houses in India 
can be both cooled and ventilated, brought 
forward a plan for discovering shoals or ob- 
structions in the way of steam vessels. Dr. 
Ranken forwarded to us a model, from 
which we had a drawing taken (plate 3, fig. 
8,). The following is the account for which 
we are indebted to the author. 
“ The apparatus is attached to the fore 
part of the vessel, and is intended to act as 
she proceeds in her course. 
“ This imperfect model is supposed to 
represent a steamer afloat, and the trough, in 
which it slides, the channel of the stream. A 
shaft or pole (1), equal to the length of the ves- 
sel, isprojected forward from the bow, where 
it floats on a level with the waterline. At the 
further extremity of this shaft is a cylin- 
drical cross-bar, (2), the length of which 
being optional, is here somewhat greater than 
the breadth of the steamer. The crossbar, 
perforating a row of feelers, (4, 5, 6, 7, 8, 9,) 
supports them in a vertical position, where 
the channel is clear, but allows them to ro- 
tate freely and to fall down, when pressed 
by any thing under water. A lever extending 
horizontally backward, with holes in it for 
receiving a weight at different distanees from 
the top of each feeler, counterpoises the 
pressure of the water and the force of the 
current on the immersed portion of the feeler. 
“ These feelers, the essential part of the 
contrivance, descend under water as far as 
the.keel, and rise above so as to be fairly in 
view from the deck of the steamer. If the 
lower ends of any of the feelers, thus im- 
mersed, come upon a shoal, sand bank, or 
sunken tree, they are forced backward and 
upward, when of course the opposite ends 
or tops, visible above water, sink forward 
and downward. The exact situation of any 
obstruction or danger to the vessel may in 
this manner be indicated in time, it is be- 
lieved, to enable the helmsman to avoid it, 
