36 ; R. HOSKING. 
used was kindly supplied by the Sydney Observatory. It 
consisted of two electro-magnets side by side. The arma- 
tures were provided with needles. Paper tape was fed 
through rollers immediately over the needle points at the 
rate of about 5 cms. per second. A special spring enabled 
the needles to travel forward a little on piercing the tape, 
and prevented the tearing of the tape. One needle was 
used for recording seconds by direct reference, through 
electrical contacts, toa standard clock. The other needle 
punctured the tape when a key was pressed at the transits 
of the meniscus in the glischrometer at the points a and b 
in the one case; or at candd inthe other. These transits 
were observed always through telescopes. 
The procedure in determining the viscosity wasas follows. 
The bath temperature was arranged to be as close to the 
desired temperature as possible, and the heating flame was 
adjusted. The pressure of air in the reservoir was raised 
or lowered to the proper level. Double readings of pressure, 
time of flow and temperature were taken. The pressure 
was next altered, and more readings were taken. In most 
cases, the determinations were repeated. Another capillary 
was then placed in position in the glischrometer and the 
series was repeated. 
The Reduction Formula.—In the Journal and Proceedings 
of the Royal Society of New South Wales are published 
three most important papers by G. H. Knibbs,’ dealing 
with the history, theory, and determination of the viscosity 
of water by the efflux method. Knibbs has shown that the 
reduction formula is 
« R* m.o.V (1 + 2kt) 
dae R) 9-pe-h.T — Ro 
sVL(L+n>) SLi +a>)T 
1 This Journal, volumes xxIx., xxx., and XXxXI. 
