forms in the
figure are copies of a series of photographs taken from the moving drops
at the rate of forty-three photographs in two seconds.[2]

[Footnote 2: For particulars see _Philosophical Magazine_, September
1890.]

Obtain a piece of good card-board as large as the figure, and having
brushed it all over on one side with thin paste, lay the figure upon it,
and press it down evenly. Place it upon a table, and cover it with a few
thicknesses of blotting-paper, and lay over all a flat piece of board
large enough to cover it. Weights sufficient to keep it all flat may be
added. This must be left all night at least, until the card is quite
dry, or else it will curl up and be useless. Now with a sharp chisel or
knife, but a chisel if possible, cut out the forty-three slits near the
edge, accurately following the outline indicated in black and white, and
keeping the slits as narrow as possible. Then cut a hole in the middle,
so as to fit the projecting part of a sewing-machine cotton-reel, and
fasten the cotton-reel on the side away from the figure with glue or
small nails. It must be fixed exactly in the middle. The edge should of
course be cut down to the outside of the black rim.

Now having found a pencil or other rod on which the cotton-reel will
freely turn, use this as an axle, and holding the disc up in front of a
looking-glass, and in a good light, slowly and steadily make it turn
round. The image of the disc seen through the slit in the looking-glass
will then perfectly represent every feature of the growing and falling
drop. As the drop grows it will gradually become too heavy to be
supported, a waist will then begin to form which will rapidly get
narrower, until the drop at last breaks away. It will be seen to
continue its fall until it has disappeared in the liquid below, but it
has not mixed with this, and so it will presently appear again, having
bounced out of the liquid. As it falls it will be seen to vibrate as the
result of the sudden release from the one-sided pull. The neck which was
drawn out will meanwhile have gathered itself in the form of a little
drop, which will then be violently hit by the oscillations of the
remaining pendant drop above, and driven down. The pendant drop will be
seen to vibrate and grow at the same time, until it again breaks away as
before, and so the phenomena are repeated.

In order to perfectly reproduce the experiment, the axle should be
firmly held upon a stand, an