Dr. Hare’s Electrical Machine, &c. Q77 
It remains to show why a large mass of electric matter will be 
discharged in a spark when there is sufficient proximity, although 
that electric matter be situated in the large globe, and attracted by 
the other, under circumstances in which, as above meneee it would 
not pass without that proximity, 
It must be evident that attraction increases, as the distance be- 
tween the bodies which exercise it lessens. Of course the attraction 
of the small globe must always act more powerfully on those portions 
of the electric fluid, which occupy the nearest parts of the positively 
excited globe. But this difference of distance, and consequent di- 
versity of attraction, increases as the globes are approximated. Thus 
that portion of the electric fluid which sustains this pre-eminent at-_ 
traction, will be accur.iulated into a conoid ; the acuteness of which, 
and attraction causing the acuteness, increasing with the proximity, 
there will at last be sufficient projectile and penetrative power to 
break through the air, and thus open a passage for the whole of the 
quantity attracted by the small negatively excited globe. 
When, by the process last described, the fluid is made to leap 
through a comparatively small interval, by the concentrated attrac- 
tion exercised by a small negative ball upon the extensive surface of 
the electric matter diffused through a large globe, the air does not 
come sufficiently condensed to resist it before it reaches its desti- 
nation, and, of course, it cannot assume the erratic form which would 
arise from repeated changes in its course, as in the instance of the 
long spark. é 
Of the Electrical Brush. 
When the machine is in active operation, and the 
prime conductor insulated; from a small knob at- 
tached to it, as at B, in the figure, the electricity 
will be sent off, as by the concomitant light to ex- 
hibit the form of a luminous brush, as represented 
in this figure at B. For the production of this phe- 
nomenon, it is necessary that the electric fluid shall 
be condensed into a'small prominent mass, so as, 
agreeably to the preceding explanation, to have 06 
penetrating power. This it cannot possess, w 
with the same intensity in the generating as a Feiss ball is posi- 
tively electrified. In that case, the electric column presents a front 
too broad to procure a passage through the surrounding non-con- 
i 7X 
