SPLASHES AND DROPS, PHOTOGRAPHY OF The photographs of splashes taken by A. M. Worthington, F.R.S., and R. S. Cole, M.A., and shown at the Royal Institution in 1894, were obtained by allowing a drop to fall in absolute darkness, and illuminating it at any desired stage by a Leyden jar discharge taking place between magnesium terminals. The following description is due to Photography. The spark was produced at the focus of a deep, silvered watch glass G (see diagram), subtending an angle of nearly 18o°, and was brought very near to the place of impact. A single quartz spectacle lens, j, was substituted for the usual lens of the camera, and thus the absorption of photo graphic rays by glass was avoided. The diagram shows the arrangement of the apparatus. Simul taneously with the drop, a metal timing sphere, D, was allowed to fall between two other insulated spheres connected to the inner coats of two large oppositely charged Leyden jars, B B, standing on the same badly conducting table. c c indicate paraffin blocks. Prom the outer coats of the jars, wires B and F led into the dark-room, and there terminated in a spark-gap between mag nesium terminals at the focus of a small concave mirror, consisting of a silvered watch glass. The
Wimshurst machine, A, was turned till the lower ball of the rough electrometer shown was lifted up and struck a glass plate ; then the sphere was liberated by tossing up by hand the remote end of the light, horizontal, pivoted rod which supported it. This broke the contact of crossed wires beneath the rod, cut off the current from the electro-magnet N in the dark-room, allowing an indiarubber catapult, M, to toss up one end of a similar horizontal lever, at whose other end the drop 1, had been supported, without adhesion, on a smoked watch glass. By this means sphere and drop were left in mid-air, free to fall at the same instant. The sphere, in its fall, discharged the inner coats of the two Leyden jars, and this pro duced a simultaneous discharge at the spark gap, between the outer coatings, thus illuminat.
ing the plate K. The timing of the spark was effected by adjusting the height of fall of the timing sphere by sliding the liberating apparatus up or down the vertical supporting rod. (See also " Bullets in Flight, Photographing.")