115 



Let me now call attention to the peculiar nature of the spark here pro- 

 duced. Observe its centre is a fine thread of blue light surrounded by a flaming 

 atmosphere which may be blown aside, and is intensely hot. Wood was lighted 

 from it to show its power of ignition. 



Now increasing the distance between the discharging points we obtain 

 our flashes at a slower rate, but with an increased intensity. This Dr. Richard- 

 son calls discharge No 2. It is simply a variety of discharge, No. 1, being a little 

 less burning, and slightly more intense. Now I connect the coatings of this 

 large Leyden jar with the terminals of the coil — one terminal with the inner, 

 aad the other with the outer coating. On makiog the discharge we observe 

 a singular alteration in the nature of the flash, which has become short, dense, 

 brilliant, and is accompanied with much noise. If we wish to increase the 

 quantity of force passing in each flash, we must either increase the size of our jar, 

 or so connect two or more jars that they operate as one. 



But in order to increase the Tension of these dischargeB we must proceed in 

 a somewhat different manner. 



If we take two or more insulated Leyden jars, and connect them in such 

 a way that the exterior coating of No. 1 shall be in metallic communication with 

 the interior coating of No. 2, and the exterior coating of No. 2 with the interior 

 coating of No. 3, and so on — coimectiDg the inside of No. 1 with one terminal of 

 our coU, and outside of the last jar with the other terminal — we obtain a flash 

 of remarkable power and quaUty. 



I have here a series of sheets of glass, each sheet coated on both sides with 

 tinfoil; each sheet is virtually a Leyden jar. 



These flat Leyden jars, if I may so call them, are connected as I have just 

 described, one side of a sheet corresponding to the inner, the other to the outer 

 coating of a Leyden jar. 



I now place the two ends of this system in communication with the dis- 

 charging terminals of the coU, and excite the coil. 



You see we obtain by tlus means a long, dense, brilliant flash accom- 

 panied with loud detonations. 



This is Dr. Eichardson's No. 4 discharge. This spark possesses almost no 

 heating power, unless much resisted. 



Now, as to the physiological effects of these four kinds of electric discharge. 



Discharge No. 1 burns, and sometimes stuns. 



No. 2 burns and stuns. 



Neither 1 nor 2 destroys life. 



No. 3 stuns, or kills, according to its intensity, and produces much con- 

 vulsion and distortion of the body, together with bruising. 



No. 4 discharge is always /ato?. Dr. Richardson says : "It kills straight- 

 way, excites scarcely any motion, and leaves the body life-like, to a degree 



