196 Proceedings of Royal Society of Edinburgh. 
(HO mm.) is vertical. In this way the movements of the first 
lever are communicated to the second lever, and they are thus 
amplified a second time. 
From the point of the second lever a thin rigid wire, g, 
passes transversely 80 mm., to be attached to a thin slip of brass (f 
bearing a fine glass syphon, m, like the syphon used in the well- 
known syphon recorder of Lord Kelvin. This strip of brass 
bearing the syphon is attached to an upright rod, h , bearing a 
circular weight at its lower end, k, delicately pivoted above and 
below, and having a fine watch spring attached to its upper end, i. 
The syphon is placed horizontally, with the longer limb, m, towards 
the front of the apparatus and with the shorter limb, Z, dipping into 
an inkpot, n. The ink used is a filtered solution of an aniline colour. 
It will be evident, on looking at the plate, that any movement of 
the second lever is thus communicated to the syphon and that 
oscillations of the syphon are controlled by the weight and the 
spring already described. The amplification of the movement is 
also greatly increased. 
The paper on which a tracing is taken is rolled out below the 
long end of the syphon by an ingenious electro-motor arrangement 
recently devised for Lord Kelvin’s syphon recorder. It will be 
remembered that in the usual form of Lord Kelvin’s syphon 
recorder the ink, electrified by the well-known “ mouse-mill,” 
spurts out on the band of paper, o m , and thus a line is recorded in a 
series of dots and without friction. The new arrangement gets rid 
of the mouse-mill. The mechanism, oo 11 (electro-magnetic), which 
draws the paper forwards at the same time vibrates up and down 
through a very short distance, and thus, in short intervals of time, 
brings the paper against the minute drop of ink at the end of the 
syphon. Thus the end of the syphon does not rub on the paper 
and there is practically no friction. The tracing appears as a line 
formed of a number of minute dots, the distances between which 
correspond to the rate of vibration of the apparatus. 
The apparatus is worked by a storage cell, p, of about 6-8 volts, 
and it runs at such a speed that 20 feet of paper are rolled out 
during the time of one revolution of the phonograph. Conse- 
quently, on a length of 20 feet of paper we obtain a record of all 
the vibrations that were recorded on 7-g-th inch of surface of 
