140 DRS. GUY BARLOW AND H. B. KEENE ON THE ANALYSIS OF SOUND. 
Harmonic. 
Frequency. 
Current-amplitude 
with iron-transformer. 
Current-amplitude 
with air-transformer. 
1 
32 
280 
215 
2 
64 
150 
10 erratic 
3 
96 
240 
210 
4 
128 
210 
20 erratic 
5 
160 
180 
205 
6 
192 
175 
30 erratic 
7 
224 
135 
200 
8 
256 
150 
20 erratic 
9 
288 
100 
190 
10 
320 
130 
40 erratic 
11 
352 
85 
180 
12 
384 
80 
20 erratic 
13 
416 
85 
160 
14 
448 
65 
20 erratic 
15 
480 
150 
160 
16 
512 
135 
120 fairly good 
17 
544 
140 
170 
18 
576 
140 
140 
19 
608 
415 
145 
20 
640 
120 
130 
21 
672 
110 
100 
22 
704 
120 
120 
23 
736 
95 
100 
24 
768 
100 
80 
25 
800 
90 
130 
29 
928 
85 
90 
32 
1024 
90 
100 
33 
1056 
70 
100 
35 
1120 
60 
130 
37 
1184 
70 
130 
40 
1280 
95 
120 
41 
1312 
80 
110 
48 
1536 
60 
90 
49 
1568 
50 
60 
After the twenty-fifth the examination of several harmonics was omitted. The table 
shows that the current produced by the air-transformer consists of practically odd 
harmonics only, until the higher frequencies are reached, and their amplitudes are 
nearly equal. This is what would be expected from the nature of the make and break. 
(4) Complex Current. 
In this experiment six maintained forks were used with their U-magnet generators in 
series. The current-amplitude and frequency were first measured for each generator 
taken separately, then all were excited and a complete analysis made. This “ spectrum” 
is given in fig. 5. It will be seen that all six primary constituents were found, together 
with their various subharmonics, and also a weak octave of the fork A, 
