OBSERVATIONS OF INTENSITY. 519 
interval, the results are found extremely accordant at several other 
stations at which observations were repeated at distant intervals. 
In the first of the subjoined tables are given the times of vibra- 
tion at Rio at the four periods referred to; and the corresponding 
times as a dipping needle. In its three last columns are shewn,— 
the number of days comprised in each interval,—the increase in the 
time of vibration owing to the loss of magnetism,—and the result- 
ing daily correction, on the supposition in each case of the loss 
having been uniform in the interval during which it occurred. 
The second table contains the corrected times of horizontal 
vibration at each of the South American stations, at the dates 
respectively inserted, —the corresponding times as a dipping 
needle,—the times of vibration as a dipping needle at Rio de 
Janeiro at the same dates, derived from the observations in the 
first table,—and the resulting intensity at each station relatively to 
unity at Rio. Thus far the results are derived from Captain King’s 
observations, unmixed with those of any other observer: but in 
order to bring Captain King’s series into connexion with the gene- 
ral body of results of other observers, the values of his intensities 
are expressed in the final column in terms of the scale in common 
use, in which the force at Paris = 1,248, and at Rio de Janeiro 
0,884; the latter being the mean of four independent determi- 
nations by the following observers, namely, 
1817 and 1820 Freycinet ........... 0,890 } 
WG27. hee gsecnosd altel tencereraepeecand 0/500 \ 0.884 
TS20. cs ee Maman cece ene tO O79 iC 7 
1836......e00008 Fitz-Roy ....seeeeees fee) 
Port St. Elena is not included in this table, as no dip was observed 
there, and the total intensity consequently cannot be computed. 
The three stations, Madeira, Teneriffe, and Port Praya, at which 
the cylinder was vibrated in the outward voyage, are also without 
dips observed by Captain King. The deficiency at Port Praya has 
been supplied from Captain Fitz-Roy’s observations and my own, 
both having been made at the same place at which Captain King’s 
intensity was observed,—Captain Fitz-Roy’s at a later, and mine at 
an earlier date. At Madeira also the dip has been supplied from 
my observations, which were made in the British consul’s garden 
at Funchal, where Captain King’s cylinder was vibrated. I have 
