248 
SCOTT'S LAST EXPEDITION 
[April 
temperature and pressure is attached beneath a small 
flag and hung 10 to 15 ft. below the balloon with balloon 
silk thread ; this silk thread is of such fine quality that 
5 miles of it only weighs 4 ozs., whilst its breaking strain 
is l£ lbs. The lower part of the instrument is again 
attached to the silk thread, which is cunningly wound on 
coned bobbins from which the balloon unwinds it without 
hitch or friction as it ascends. 
In order to spare the silk any jerk as the balloon is 
released two pieces of string united with a slow match 
carry the strain between the instrument and the balloon 
until the slow match is consumed. 
The balloon takes about a quarter of an hour to inflate ; 
the slow match is then lit, and the balloon released ; with 
a weight of 8 ozs. and a lifting power of z\ lbs. it rises 
rapidly. After it is lost to ordinary vision it can be 
followed with glasses as mile after mile of thread runs 
out. Theoretically, if strain is put on the silk thread it 
should break between the instrument and the balloon, 
leaving the former free to drop, when the thread can be 
followed up and the instrument with its record recovered. 
To-day this was tried with a dummy instrument, but 
the thread broke close to the bobbins. In the afternoon 
a double thread was tried, and this acted successfully. 
To-day I allotted the ponies for exercise. Bowers, 
Cherry-Garrard, Hooper, Clissold, P.O. Evans, and Crean 
take animals, besides Anton and Oatcs. I have had to 
warn people that they will not necessarily lead the ponies 
which they now tend. 
Wilson is very busy making sketches. 
