al 
Miscellanies. 171 
also the converse, that a current of quantity can be produced by one 
of intensity. 
The third section relates to the effect of interposing different sub- 
stances between the conductor which transmits the current from the 
battery, and that which is arranged to receive the induced current. 
All good conducting substances are found to screen the inducing ac- 
tion, and this screening effect is shown, by the detail of a variety of - 
experiments, to be the result of the neutralizing action of a current, 
induced in the interposed body. This neutralizing current is sepa- 
rately examined, and its direction found to be the same as that of the 
battery current. The question is then raised, how two currents in 
the same direction can counteract each other? An answer to this 
question is given in a subsequent part of the paper. 
The fourth section relates to the discovery of induced Eno TA of 
the third, fourth, and fifth orders ;—that is, to the fact that the second 
current is found capable of inducing a third current, and this latter 
again another, and so on. The properties of these new currents are 
next examined, and the screening influence is found to take place be- 
tween them; quantity is induced from intensity, and conversely; 
magnetism is developed in soft iron; decomposition is effected, and 
intense shocks are obtained, even from the current of the fourth or- 
der. A remarkable and i impor orient fact is stated in reference. to the 
direction of these currents. If the direction of the battery current 
_ and that of the second be called plus, then the direction of the third 
current will be minus, of the fourth current plus, of the fifth minus, 
- andso on. The application of the fact of these alternations is made 
_ to the explanation of the phenomenon of screening before mentioned, 
and also to. the improvement of the magneto-electrical machine. 
The last part of the paper relates to the discovery of secondary 
currents, and of currents of the several orders, in the discharge of 
ordinary electricity. Shocks are obtained from these; the screening 
influence of good conductors is shown to take place; magnetism is 
<a See ; and the alternations in the direction are found to exist as 
: | the currents from galvanic induction. Some remarkable results 
- 
- « “are given in reference to the great distance at which the induction 
. takes place. Experiments are detailed in which needles were made 
Magnetic, when the conductors were removed to the distance o 
= twelve feet from each anst 
ee Prof. Henry made a verbal communication, during the course of 
which he illustrated, pcre eo the phenomena developed in 
his paper, 
November 16, 1838—The Committee on the solar eclipse of the 
18th of September, made a further Report in part, comprising the fol- 
owing observations :— 
