206 . Miscellanies. 



ced magnetism withheld, as the armatures recede from the electro- 

 magnet. The armatures are nicely fixed upon an axis, and made 

 to descend parallel to the faces of the magnet, and as they are at- 

 tracted and suffered to pass, the momentum which at the time of pas- 

 sage is only left, btings the others into action. 



aaaa are the armatures — b the electro-magnet, placed at an an- 

 gle towards them and wrapped with a single coil of coated copper 

 wire — dd 1 two small brass stars placed on each side of the armatures, 

 and soldered to the axis. The points of the stars are made to de- 

 scend into quicksilver troughs, placed underneath them, and to come 

 into contact with the mercury at the time the armatures approach the 

 electro-magnet, and to revolve out of the quicksilver as they recede 

 from the electro-magnet ; it is only at the time of their contact, that the 

 current of galvano-magnetism, proceeding from p, where the positive 

 pole of a galvanic element is placed, can pass through the coil to d f 

 and along the axis by the intervention of the small stars, to n where 

 the corresponding negative wire of the element is placed. The in- 

 strument will revolve for several hours. 



5. Remarks on Steam, as a Conductor of Electricity. 



Frederick, Md. Jan. 13, 1834. 



Prof. Silliman — Sir — Upon reading an article in the April No. 

 of your Journal for 1832 with the caption " Steamboats protected 

 from the effects of Lightning" it appeared to me that the writer had 

 subjected himself to unnecessary trouble and expense, to assure him- 

 self of a fact whose existence he might have predicted with abso- 

 lute certainty. And in what manner ? By asking the question, why 

 is it, that an electrical machine cannot be charged in a moist atmos- 

 phere ? Clearly, because the moist atmosphere, being an excellent 

 conductor of Electricity, dissipates or conducts it away as fast as the 

 machine generates it. Now, the only difference between a moist at- 

 mosphere and steam, is, that the vapor in the latter case is connect- 

 ed with a larger proportion of caloric. And therefore, methinks 

 there is nothing novel in steam being a conductor of electricity. The 

 writer goes on to say, "It is therefore pretty well proved that "the 

 steam generated in a steamboat completely protects it from the effects 

 of lightning." So far from " the steam generated in a steamboat." 

 protecting it from the effects of lightning, it may be proved, we think, 

 from the writer's arguments that it has an opposite tendency. What 

 does he say. These are his words. H The electricity of the clouds 



