458 Prof. Ritchie on Electricity and Magnetism. 
state with extreme rapidity. To produce a sensation the ex- 
citing cause must continue to act for a certain length of time 
depending on the delicacy of the organ. The eye being the 
most delicate is affected by a series of vibrations continuing 
during a very short period; and hence a comparatively short 
wire formed into a coil will exhibit light when the circuit is 
broken before any sensible shock is experienced. 
By continuing to lengthen the coil the series of vibrations 
will continue during a longer period, but they may not follow 
each other with sufficient rapidity to constitute light. When 
any part of the body is placed in the circuit when the metallic 
contact is broken, the electricity belonging to that part of the 
body is suddenly forced into a corresponding polar arrange- 
ment accompanied by that peculiar sensation termed a shock. 
Hence in the case of five or six feet of imperfectly conducting 
substances, such as the liquids of the body, a certain length of 
time must be required to allow the induction to take place. 
3. If these views be correct, the electric fluid instead of 
being an imponderable agent possesses one of the essential 
properties of ponderable matter. When a body is put in 
motion it will communicate a portion of its motion to other 
matter, but not without Josimg a corresponding quantity of 
its own motion. Hence, agreeably to the experiments of 
Mr. Faraday, when the electricity of one wire is forced to induce 
electric polarity on that belonging to another wire, the mo- 
mentum of the first suffers a corresponding reduction. Again, 
the motion of the electricity of a wire towards a state of po- 
larity will continue after the inducing cause has been removed, 
thus exhibiting in another point of view the same property of 
ponderable matter, viz. the inertia of matter, or in this case its 
tendency to continue in motion after the impulse which first 
produced the motion has ceased. 
If these views be correct we have no right to expect that 
bodies at different temperatures, or differently electrified or 
magnetized, will have different weights, since in each of these 
states they contain exactly the same quantity of ponderable 
and improperly called imponderable matter. 
It is a well-known fact that we receive a more powerful - 
shock when electricity is being induced on the body than 
when the induced electricity is returning to its natural state. 
This is what might be expected from considering the energy 
and quantity of the exciting agents employed, these being 
either a powerful voltaic battery, or the immense quantity of 
electricity put in rapid motion in a large mass of soft iron. 
If these views be correct again, it is obvious that as we hear 
by means of vibrations, so we see by means of vibrations, we 
