A new apparatus devised by the lecturer, the Recording Crescograph, is
described in the Transactions of the Royal Society, and of the Bose
Institute. By a compound system of levers the magnification is raised to
10,000 but this is not without great technical difficulties, which cost
five years of efforts to overcome. Thus the levers require to be
extremely light; this was secured by the use of an alloy of aluminium
used in the construction of Zeppelins: this combines lightness with
rigidity. Another difficulty almost unsuperable arises from the friction
at the bearings of the fulcrum, the best watch jewels made of ruby were
employed, but the supply was cut off from Germany by the war. This
proved a blessing in disguise, for it forced the lecturer to devise a
new principle of suspension using local material. This was found in
practice to be far superior to jewel bearings, which became clogged by
invisible dust particles present in the air. With this Recording
Crescograph many phenomena of extreme interest have been discovered. The
plant itself not only recorded its normal rate of growth but the
slightest change induced in it by the action of different forces. So
delicate was the apparatus that it analysed growth into a series of
pulses, a sudden shooting out followed by a partial recoil. It showed
how the growth of the plant was retarded by a mere touch, and the time
it took the plant to recover from the effect of contact, and all these
in course of a few seconds. The effect of different food on growth, the
effect of different drugs, or living capacity these and many more became
revealed by the automatic record made by the plant. This has opened out
fresh and more exact method of medical inquiry, and of practical
agriculture.