60 Lovering and Bond on Magnetic Observations at Cambridge. 
not be altered from one set of observations to another. Hereafter, 
as the observations will be made with Lloyd’s Declination Magnet- 
ometer and a fixed telescope, we shall not be subjected to this in- 
convenience. 
For greater accuracy, the absolute variation assigned to 100 of 
the scale for any period should not depend upon a single set of 
readings. But the process which has been described for finding the 
real value of any part of the scale should be repeated as often as 
possible during the days of regular observations. ‘Thus we have : 
June 21 at 8" 0’ P. M. Gott. M. T., the abso- 
lute variation : == 90 20’ 00" at 100 of the scale. 
June 22 at 11° 15’ A. M. s§ Ss =9 21 14 ce ce 
« 9512 2929P,M. « “ =9 2234 « «“ 
“ 98 9 35 « « «“ =9249 « « 
cD OMe Gmce ce & — 1 a. “ “6 
«© & «12 00 M. «“ « =9 2053 « « 
“« 301195P.M. « “ =9 1829 « « 
July 1 045 « «“ «“ =9 1857 “ «“ 
cc iT en 99 1i 25 ce «¢ 74 — 20 86 ce ec 
Mean for June . : 3 : ==/9) (20/59 6 a 
October 20 at 7° 30'P. M. “ « =9 19 16 EE ct 
“« 216 940 « «& « =9 18299 « « 
“« 9210 5 “« «& «“ =91640 « ee 
« 93 B15 “ « «“ 0019 ite See « 
“ 24% 2 10 arias Ge = 16 58 & ‘“ 
ve Woneng arte ee =91654 * « 
CGRP SDE CROAT: “Ween BIC 36 = 9815 56 ee ee 
Mean for October 3 ; . 8) ily) 24) ce es 
We now pass from the absolute value in declination of 100 of the 
seale to the absolute declination in this way. If the absolute varia- 
