234
676
These have at one end a brass ring and terminal for a wire, and at the
other both external and internal threads, into which is fixed a stub of
white metal with a conical end. For use with an induction machine.
676 DISCHARGE POINTS j® 0 1 0 ) 4/4 19th C.
Base length 148; height 260; diameter of spheres 20
Walnut and ebonite base holds four brass rods at the top of which are
screwed spheres of steel, copper, zinc, and carbon. A spark discharge
varies according to material.
677 DISCHARGERS (499) 3/4 19th C.
Two curved copper rods with brass balls are joinedat a brass
compass joint. On each rod is an ebonite handle, movable on
a brass boss that runs on the rod and clamps in position by a
screw. Length of arm 465.
Two straight brass rods with brass balls are joined at the hanHL
in the manner of a mariners one-handed divider. The handle is
of glass, and is broken. Overall length 470.
677
678 DISCHARGER: PERFORATING (500)
Base 190 x 1 jj|; height to top of tube 248
3/4 19th C.
Square mahogany base has offset brass p la te « ! square) on the upper
p d e , and on underside four holes-at the corners. It afio supports a glass
j tube in brass mounts, with a brass ball at the top. The brass plate has a
brass terminal in the form of a double sphere at one side. A brass rod
(length 280) with a pointed lower end is suspended above the centre of
the plate, running through a brass ball of the same size as the ball at the
top of the glass tube, and linked to it by a brass connecting rod.
679
To perform the experiment of piercing a pane of glass, a short
glass cylinder with a metal spike at the centre is placed on the square
brass plate (this part is now lost). The pane is rested on the cylinder and
the pointed rod brought down just to touch the glass. A powerful spark
from a battery of Leyden jars will produce a hole. Deschanel (1877),
588-589, fig. 400; Guillemin (1891), 245, fig. 145.
679 DISCHARGER '© oM 3/4 19th C.
Base diameter 90; height to curved bracket 425
Round mahogany base holds a glass tube with curved brass tube at top,
through which runs an adjustable rod, which ends in a concave brass
dome. Below, on collar, also adjustable, is a ring (diameter 90) Ion an
adjustable bar; below on another adjustable collar is a bent bar terminating
in a brass ball. At the top and on both collars there are gap rings
into which can be inserted the rings of the hand-held discharger. This
has three links, with brass rod, glass-handle, and ball at the end.
680 FLICKER TUBE (524) 3/4 19th C.
Length 1,200; diameter 23
Glass tube has diamonds of tin-foil on the outside in the form of a spiral.
At each end are brass end caps with terminals for wires. By arranging
small pieces of tin-foil at small distances from each other on an insulating
surface, in this case a tube, and by joining the ends to an electrical
machine, sparks can be seen at all the joins simultaneously. Also named
a spangled tube. A tube of similalength as here was sold by Ernecke of
Berlin. Deschanel (ISfiM 553, fig. 370; Erneckei<H905], 225, fig.
8033.
680
681 DISCHARGER (525) 3/4 19th C.
Base diameter 151 ; overall height 263
Heavy, black-painted cast iron base supports wooden pillar, painted
black, with brass side bracket to bent glass tube. On top is a brass