Lovering and Bond on Magnetic Observations at Cambridge. 41 
and these eight minima: 
Readings of the Scale. 
1st at 3° 14’ P. M. of September 20 = 112. 
Qd “5 46 OC os i ——seL LG. 
Sd ey op, “ ee 
Reading at 8" 16’ P. M. 109. 
Ath ** 8 26 ee Cis Fe = 1195. 
5th *°O 46 A.M. a 21 = 116. 
Reading at 1" 06’ A. M. 98.5. 
6th ** 1 54 OS ots cama 
7th ‘*6 06 Ke re 66 == 115.5, 
Sthies 2a ole eevee ce Sst O8s 
The whole range of the Magnetometer during this day is 45’.5. 
The smallest elongation from the meridian is at 8" 26’ P. M. and the 
greatest at 4°56’ A. M., as the lowest number of the scale indi- 
cates greatest declination. But these like the rest of the maxima 
and minima for this day are mere lawless excursions caused by 
sudden derangements and have no connexion with the regular diur- 
nal magnetic curve. Between the 3d and 4th minima the bar moves 
to 109' or 14’ in arc in the space of 20 minutes and then falls back 
eastward again. So between the 5th and 6th minima the bar 
moves to 98’.5 of the scale or 18’ forward and back again in 1° 8, 
The time occupied in going from the 2d or greatest maximum to the 
7th minimum is only 1" 10’ although the space is 36’ or three times 
the ordinary daily range of the magnetic meridian for this month. 
If these perturbations were less frequent and not spread over the 
whole 24 hours means might be devised of shutting out their in- 
fluence and interpolating the true daily curve in the gap left by their 
removal. But on this day no safe way of making the reduction 
presents itself and the times of maximum and minimum are both 
left indeterminate. 
6 
