Miscellanies. 
Pome I would suggest what may be called a compound slecisiaae be 
[a 4, het.” I propose to have a seties of circles, encircling each other 
any definite extent required. I would after having formed a pris % 
| ee - electro-magnet have it insulated on the outer surface; then place 
Rs either a cylinder of iron or a succession of wires, until they have ee 
| encircled the primary electro-magnet; then make a helix of copper. 
Wire in the usual manner; (I would prefer platinum wire to make the 
helix; ) after having made a number suflicient to try an experiment, 
unite them by a plate of iron, either entire or in rims corresponding * 
| to each magnet. Talso suggest the trial of brass cylinders over each 
successive electro-magnet to cut off the radiations of electricity ; ‘this * i 
will have either the effect to increase or decrease the magnetic power ;_ = 
experiments thereon must determine. Not having leisure to pursue the = 
: subject myself, I offer these suggestions for i public good steoegh & 
the medium of your highly valuable Journa 
Yours respectfully, 
Jonas Humpert, Jr., Medical Electrician, 
327 Broome St., New York City. — 
To tnx Evrrors—Gent. :—I have for several years spent much 
of my leisure time in collecting the fresh-water and Jand shells of this 
state, and have on hand a Jarge number of species of Unio, Marga- 
Titana, (Alasmodonta,) Anodonta, Cyclas, Ancylas, Helix, Polygyra, 
| Helecina, Pupa, Succinea, Cyclostoma, Planorbis, Physa, Lymneus, 
; Melania, Anctlosa, Valvata, and Paludina, which I am desirous of 
exchanging for such native and foreign species as are not in my col- 
lection. My shells are generally very perfect; the Naiades, which 
are mostly from the Scioto River and its tributaries, are remarkably 
so. -Lam particularly desirous of exchanging for native shells in the 
above genera, especially for native and foreign Naiades. = 
Tam also collecting the Insects of this state, and would be wie : 
to exchange them for native and foreign labelled species. A 
I can label my shells with the names by whick Ania are known: a .. 
. aur western naturalists. Pe aaa ; 
- Either this fall or early in the spring I will ici ayself the 
of es for your acceptance a suit of western shells, 
I am respectfully, ae obedient se 
| 7. Exchanges of American Shells and Insects. ae 
at 
oe Ohio, Novena 14, 1839. 
8 The Railway Magazine and Steam Ee in ion ‘Eo. 2 
ited by John Herapath Esq. London. Penta by 3: Wyld, ‘Byo. Pee 
Monthly=—This i is a periodical work devoted chiefly | to what i ae 
* 
