128 ANNUAL OF SCIENTIFIC DISCOVERY. 



red to a series of oscillations in the discharge of the jar. If we adopt 

 the hypothesis of a single fluid, then we shall be obliged to admit that 

 the equilibrium of the fluid, after a discharge takes place, by a series 

 of oscillations, gradually diminishes in intensity and magnitude. He 

 had been enabled to show effects from five of these waves in succes- 

 sion. The means used for determining the existence of these waves 

 was that of the magnetization of steel needles, introduced into the 

 axis of a spiral. A needle of this kind, it is well known, is suscepti- 

 ble of receiving a definite amount of magnetism, which is called it? 

 saturation. Now, if the needle be of such a size as to be magnetized 

 to saturation by the principal discharge, it will corne out of the spiral 

 magnetized to a less degree than that of saturation, by the amount of 

 the adverse influence of the oscillations in the opposite direction to 

 that of the principal discharge. If the quantity of electricity be in- 

 creased, the power of the second wave may be so exalted that the 

 needle will exhibit no magnetism ; the whole effect of the first or 

 principal wave will be neutralized by the action of the second. If the 

 quantity of electricity be greater than this, then the needle will be 

 magnetized in an opposite direction. If the electricity be still more 

 increased, the needle will again exhibit a change in its polarity, and so 

 on in succession, as the power of the successive waves is increased. 



INTENSITY OF THE ELECTRIC SPARK. 



M. MASSON, in a paper presented to the French Academy on May 

 20, gives the results of an investigation of some questions connected 

 with the relations existing between heat, light, and electricity. He 

 finds that the intensity of the electric spark is in an inverse ratio to 

 the resistance of the circuit. " In comparing the intensities of many 

 sparks produced simultaneously in the same circuit by a discharge of 

 the condenser, I have arrived at the following results: 1. When 

 several sparks are produced simultaneously in tho same circuit by the 

 discharge of a battery, their intensity is different and proportional for 

 each to the square of the quantity of. electricity furnished by the con- 

 denser, and to the tension of the electric fluid at the point of explosion. 

 2. If the negative pole of a spark communicates with the ground, the 

 positive pole being isolated, the illuminating power is twice as great 

 as if the positive pole communicated with the ground, and the quanti- 

 ties of electricity producing the explosion in these two cases are to 



each other as \/2 to 1. In gases, the resistance to electric explosion 

 is proportional to their pressure. 



SINGULAR PROPERTY, AND EXTRAORDINARY SIZE AND LENGTH, 



OF THE SECONDARY SPARK. 



IN experimenting with my great magnet, a new property of the sec- 

 ondary spark has been discovered, and some very interesting facts eli- 

 cited. I will premise that the helix, nearly a foot in diameter each way, 

 when charged by the battery, draws up within it in a vertical position 

 a huge bar of iron weighing 300 pounds, through a distance of ten 



