ANA Correspondence of J. Nickles. 
The circumference of the electro-magnets is at intervals terminated by 
he magneti 
brass plates so arranged as to serve to interrupt t gnetic circuit, 
As long as the iron portion of the circumference ye deg me arm 
ture, it “tends to separate itself from it, and carries in its movement the 
whole mass of the electro-magnet with the axis which sa ftaspte it and 
the fly-wheel on the latter; but at the moment when contact takes place, 
app 
ratus is neither powerful nor economical. It would ‘ better to employ 
circular electro- magnets with two poles. 
The electro-magnetic machine with trifurcate magnets is more pow- 
erful, since the action between the magnet and armature is not exerted 
at the time of contact. But I may describe these machines at a future 
time with some details, and now “ee only that neither of them resolves 
the oo of an economical m 
The only galvanic battery on Saieliion: which has any novelty, is 
that called the electro- hydro-dynamic, by M. Chenot, in which he us 
the sponge of iron, of which he is the discoverer, as already commu- 
nicated. The same inventor has a machine which is an interesting ap- 
plication of electro-magnetism to the dressing of iron ores. Thes 
ores, being magnetic, are thus easily separated from the gangue and 
made ready for the furnace. ‘The machine is a drum carrying electro- 
magnets on its circumference. A screen carries the impure ore under the 
drum where the poles of the electro-magnets take up the oxyd of iron and 
leave the gangue on the frame to be transported by it into an enclosure 
one side. As the drum moves on in rotation, the galvanic fluid is made 
to leave the ria range of magnets and act upon the next; the ore of 
the first is thus dropped, while the next is taking its load. M. Chenot 
0 
of the magnificent galvanoplastic products, there are different in 
of pape telegraph. 
There is the signal telegraph of M. Bréguet, in which the same sig- 
nals are made as sometimes used in the ordinary aerial ene 
ceiver, 8 positions in its turn in place of 26 which the alphabet requires, 
will have some idea of the signal telegraph which has been adopted 
a the administration of telegraphic lines in France—adopted not with- 
ss for ral 
out resisting progress for several years, and denying the benefits of the 
- Seba telegraph for a long period after this invention was employed 
e United 
tat 
Eiheo ee exhibits a telegraph in which manipulation is — a 
re with a finger-board, having as many keys as letters. A arbor in 
this box tends constantly to move under a clock movement and pa 
in its motion the wheel which opens or closes the circuit ; but it is re- 
tained by a catch which pressure on a key raises,—a simple arrange- 
— for producing the breaks in the current. The receiver is that 
of the primitive telegraph. 
