Magnetism as a Mode of Motion. 119 
Tables V and VI exhibit an approximation to the proportion, 
C:1':: T: M, but the approximation does not come within the 
limits of probable error. As no attention is paid in these two 
Tables to the positive and negative signs, we could not reason- 
ably expect so satisfactory results as in Tables JI and III. 
“Table VIII. Sums, without regard of sign, of Coefficients 
of Magnetic Irregularity (in terms of Horizontal Force) for each 
Year, from 1841 to 1857, including all Days of Record of Great 
ee cicel Disturbance.” The proportion C: T:: T: M, gives 
eh 
Theoretical value, F . 001218 
Observed “6 - : - 001208 
Probable error, . : . 000066 
“Table IX. Sums, without regard of sign, of Coefficients of 
Magnetic Irregularity (in terms of Horizontal Force) for each 
Year, from 1841 to 1857, including only those Days of Great 
Magnetic Disturbance, in which records were made by the three 
Instruments,” 
Theoretical value of M, . : ‘ «  ORTIAT 
= rred “ “ a ‘ * - ‘001150 
Probable error, ; I ‘ 000081 
In addition to these numerical coincidences, the following 
ty in Mr, Airy’s paper appear to me to be specially note- 
Worthy. 
1. “The Ageregate for the Westerly Force... . (taken in 
Comparison with that for the Northerly Force), appears to show 
that, on the whole, the direction for the Disturbing Force is 10° 
to the east of south ;” p. 628. This indicates a line of mean 
disturbance about mid way between the magnetic meridian (which 
at London, is about N. 24° W.}, and the solar meridian, or mid- 
Way between the meridians of decussation in the two sets of 
Principal spirals, to which I have referred. : 
2. “Sometimes two waves in one direction correspond nearly 
With one in the other direction. . . . . A more requent relation 
pete to be, that the evanescence of one wave corresponds 
ith the maximum of the other;” p. 685. 
7 “The most striking oavauehics in the last line (of Tables 
ape IX) are the following: Secu 
rst, the almost exaet equality of the Mean Coefficients o 
regularity in the three clements. . . « With reference 
'o their physical import, I think it likely that the equality of Co- 
efficients of Irregularity may hereafter prove to be one of the 
rite important of the facts of observation.” ae 
Second, the near agreement in the number of Irregularities 
te ' Westerly and for Northerly Force. 
: 
pro tie ti ae oach to equality appears to be still more important, in view of the 
y—C:T::T:M—pzno 
