\(^\^^^^^^ the Induction Coil, - ■"'^''^ 445 



inch, both become white-hot, the negative being rather hotter 

 than the positive ; and on substituting fine iron wires for the 

 platina points, both enter into combustion. Fine platina wires 

 become white-hot at the ends, melt, and run back into globules. 

 7. Through the flame of alcohol a flood of sparks will pass 

 between 8 and 9 inches in length, producing a curious zigzag 

 circuit, and accompanied with very loud crepitations. 

 >-■ 8. In an exhausted receiver, 3 feet in length and 4 inches in dia- 

 meter, a splendid ribbon of light is produced of the most exqui- 

 site colours, the centre line being bright, and surrounded by an 

 intense crimson light, shading off into violet and purple. I have 

 only yet tried a receiver of these dimensions, but should consider 

 from appearances that the light would pervade a much longer 

 vacuum. 



9. I have only tried Gassiot^s cascade in a flower vase 10 

 inches high, but there can be no doubt that a flower vase of 2 

 or 3 feet in height would be equally well illuminated, as 1 was 

 obliged to use only 3 or 4 cells, otherwise the action of the machine 

 was too strong. The contrast in the appearance of the light on 

 reversing the current is most beautifully exhibited. On making 

 the inside of the vase positive, the electricity appears to flow in 

 an immense sheet out over the edge to a considerable distance, 

 and fall upon the plate of the pump ; but on reversing the cur- 

 rent, a totally diffbrent appearance is produced : the sheet appears 

 now to envelope the vase more closely, and to flow up and turn 

 in over the rim,' the direction of the current in each case being 

 too decided to be mistaken. 



10. I have not yet heard of any effects from a single machine 

 which have at all approximated to these results ; and as I believe 

 that the arrangement is not only more powerful, but possesses 

 important advantages over that adopted by M. Ruhmkorff, I 

 have not hesitated to bring it before the scientific world. I 

 find it, however, absolutely necessary to identify myself with the 

 process of manufacture, as even the most careful workmen are 

 apt to overlook what may appear- to them trifles, but which are, 

 however, in fact the main causes of success or failure. I am also 

 satisfied that the foregoing effects, although of an unusual cha- 

 racter, are but trifles compared with what may be obtained from 

 a judicious extension and modification of the principles ; and I 

 even doubt whether I have yet attained the maximum effect from 

 the secondary wire of the machine which I have now described, 

 as the secondary current, although increased by extra battery 

 power, depends more upon the magnetic intensity of the iron 

 core than upon any modified conditions of the battery current 

 and primary coil, except so far as they shall combine to exalt the 

 magnetic condition of the included core. 



