138 
PROFESSOR A. .M. WORTHIXGTOX AXD MR. R. S. COLE 
Devonport, Mr. Cole, and after taking advice from Professor Boys, and excnauging- 
my old self-induction spark for the much shorter Leyden-jar spark that had been 
employed by Lord Rayleigh" for a similar purpose, we obtained after a few weeks 
of failure, some preliminary photographs which were shown at the lloyal Institution, 
May 18, 1894.t These photographs, while amply confirming the old drawings, gaYe 
so much new and detailed information as to make it seem worth while to go oxer the 
whole ground again. Of this review, which is our joint work, the following com¬ 
munication is the first instalment.—A. ]\f. W. 
Fig. 1. 
Method of Taking the Photographs .—-The method consists in letting fall, simuL 
taneously vdth the drop, a metal timing-sphere. This in its fall passes between two 
other insulated spheres connected to the inner coats of twm large, oppositely-charged 
Ley den-jars that stand on the same badly-conducting table. From the outer coats 
of these jarg=^wires are led into the dark room, and there terminate in a spark-gap 
between magnesium terminals at the focus of a small concave mirror. The timing- 
sphere, in it.s fall, discharges the inner coatings of the two Leyden-jars, and this 
produces a simultaneous discharge at the spark-gap between the outer coatings, and 
it is this that illuminates the splash. 
Fig, 1 is a magnetic releasing key, of which two were used on the same electric 
* See ‘Xatnre,’ July 16, 1891, p. 249. 
t ‘ Ou tbe Splash of a Drop and Allied Phenomena ’—a Friday Evening Discourse. This will be 
found to contain a resume of all previous papers. See also in ‘ Xature,’ July 5, 1894, a paper by 
Mr. Cole. 
