998 ME. F. JENKIN’S EXPEEIMENTAL EESEAECHES ON THE TEANSMISSION 
required, little holes were cut in the paper to make contacts in pairs, each pair half the 
length of those used for a dot. In fig. 9 these short openings are shown where the 
word “space” is written. This arrangement was perfectly successful with 1500 knots 
in circuit on the very first trial ; and although other strips of paper were tried with 
other proportions between the contacts, none gave better results than those first adopted. 
When the paper was steadily drawn along, the signals appeared on the galvanometer 
with all the regularity that could be wished ; during the pauses, the light stood trem- 
bling at one division on the scale, a dot caused a slight rise followed by an equal fall, 
and the dashes produced a greater and longer oscillation, at the end of which the spot 
always returned to the one constant final strength. 
A still more decisive test was next made, by substituting a relay and Morse marker 
for the galvanometer ; fig. 10, Plate L. is an exact copy of the signals which were then 
received, and shows faithfully the slight irregularities which did occur. The only serious 
flaw in the whole set of signals is shown at the beginning, between A and B, where some 
dots and a space contact made only unintelligible marks. This flaw invariably occurred at 
the same place; it was shown equally by the galvanometer and the relay, and for some 
time the cause could not he discovered. By carefully watching the paper strip, it was 
;at last seen that when the joint of the endless band passed through the rollers E (fig. 8} 
a little hitch or pause occurred, and that this slight irregularity of speed caused a corre- 
sponding confusion in three signals. This accident showed the accuracy of proportion 
required between the various contacts. 
Taking this hitch as the beginning, we next see six well-spaced dashes, three pah’s 
of dots and dashes, one space, one dot, one space, one dash, a long pause, a dot, a long 
pause, a dash, a short pause, a dot, a dash, and a succession of dots. 
In this series every possible difficulty which could arise from interference or con- 
fusion was encountered and successfully overcome. The rate was about forty-five dots 
per minute, and the oscillations for a dot must have been about 5 per cent.* 
Signals sent at a much higher rate could have been distinctly received, but the 
drawing-rollers could only be driven at one speed. 
The apparatus was next tried with 1800 knots in circuit: the signals could be read 
without difficulty on the galvanometer ; but to increase the range and to facilitate the 
adjustment of the relay the battery power was increased, when not only could the 
regular dots and dashes be received, but even the short space contacts gave distinct 
legible signals ; so that the three sets of signals of three different lengths appeared, 
without confusion, recorded by the relay. The shortest signals were received at the 
rate of ninety per minute ; and from Table VI. it will be seen that even sixty dots per 
minute through this length reduced the oscillations to less than 1 per cent, of the per- > 
manent maximum s-trength. Hence we may conclude that, the means described, or by ■ 
* When the relay was used the galvanometer could not be observed, for the motion of the soft iron used 
in the relay induced short currents, causing rapid vibrations of the spot of light. 
