1016 ME. F. JENKIN’S EXPEEIMENTAL EESEAECHES ON THE TEANSmSSION 
the paper, the reciprocals of the numbers in the third column give the amplitude of the 
dot measured as a function of the maximum permanent current*. For instance, if each 
dot occupied a period a, the amplitude of variation in the received cmi'ent would be 
3 - 3 ^ 8 111 of the maximum permanent current, or would be 0-02956 per cent, of that 
current. 
The fourth column is obtained by multiplying the numbers in the third column into 
a constant The numbers so obtained express the reciprocals of the amplitudes which 
would result if, instead of being subjected to the harmonic variation previously described, 
the end operated on had been maintained at the maximum potential for the first half of 
the periods 0, and at the minimum during the second half. This was precisely the 
condition fulfilled when dots were sent in the experiments described. The potential of 
one pole of the battery was maintained at the sending end of the cable during one half 
of each dot, and the potential of the earth was maintained during the other half. 
The fifth column contains the product of the reciprocals of the numbers in the fom-th 
column multiplied into 100 , and gives therefore the amplitudes produced by dots made 
as in the experiments occupying the various periods in the first column, and these ampli= 
tudes are moreover expressed in percentages of the maximum received current, as in the 
rest of the paper. 
The product of the reciprocals of the times entered in the first column, multiplied 
into 60, will give a series of numbers corresponding to the number of dots per minute 
in terms of a. This series, expressing “ speeds,” is entered in the sixth column. 
The numbers in the fifth and sixth columns used as coordinates give the curve, shown 
in fig. 11, Plate LI., corresponding most accurately with the observed speeds and ampli- 
tudes. 
The scale of amplitudes, shown in full lines, corresponds to the numbers in the fifth- 
column, and the scale of times, shown by dotted lines, corresponds to the values of 
^ when C 4 is taken as unity. 
When in any case the amplitude corresponding to a given number of dots is known, the 
actual value of a can at once be determined from this curve. Thus observation (Table TV.) 
showed that for a length of 1500 knots of cable -plOO knots of resistance, with 92 beats 
or 46 dots per minute, the amplitude was 5 per cent., and by the curve we find that this 
amplitude corresponded to a speed of 16*4x^; hence 46=16*4x^, or a=0"*3565f. 
From this value the electrostatical capacity per unit of length, and the specific inductive 
capacity of the dielectric could be determined. These points will, however, be more 
fully treated of in the second part of this paper. 
* The second column only contains tlie value of a certain quantity i used in the fomula by which the 
third column is calculated. 
t It should be observed that inasmuch as this observation does not exactly faU on the curve, so the value 
of a differs a little from that which would be calculated by the curve alone, as presently to be described. 
