568 MR J. A. BROUN ON THE 
Lerroy (Toronto, 1841—48),* Kay (Hobarton, 1841—48),+ Smyrue (St Helena, 
1841—47),{ Wiimor and CLerk (Cape of Good Hope, 1841-46).§ -As the 
different results obtained by Drs Lamont and Wo tr depend wholly on the value 
to be given to the first series of observations, and the interpretation especially 
of GrLprIn’s series, these require the most careful consideration. The essential 
details relative to the other series will be found in the notes below. 
11. The yearly mean ranges corresponding to each month have been obtained 
for each place in the same manner as for Trevandrum, and they have been 
projected in the curves, Plate XX XIX. From these means we obtain the 
following epochs and ranges ;— 
Munich, Maximum, 1848-9 = 11°53 Minimum, 1844:25 = 6°56 
Dublin, = 1848°9 = 13”31 2 1844°25 = 8°76 
Makerstoun, 4 ' ; ; : ; a 1844°25 = 7°86 
Toronto, : : ; ; : : : b 1843°9 = 8°47 
St Helena, : : ‘ : ‘ : é a 1843742 = 3°44 
Hobarton, ; : ? : ; : ; be 1843:45 sco 
Cape of Good Hope, ; : : z : ts GHA ES es HEOR 
The hourly observations were not continued at the last five stations suffi- 
ciently long to give the time of maximum. We deduce from the southern 
stations the minimum in 1843°43 nearly, and from the southern stations 184425, 
or we have nearly for the mean epochs, maximum 1848-9, minimum 1843-85. 
12. The period preceding this depends on Gauss’s observations ; they give a 
double maximum of nearly equal value in 1836°9 and 1888°3 (see Plate 
XXXIX.), the former of which, however, has the greatest weight; we may per- 
haps be able to take with no great error the maximum in 1837:°5=137-04| 
The minimum occurred before 1834:7, probably near 1833°5, if we may judge 
from SCHWABE’s observations, to which reference will be made hereafter. 
13. From ArAGo’s observations, we derive the well-marked epochs, maximum 
1829-7 =13"74, minimum 1824:°3=7’75. (See Plate XX XIX.) | 
14. Beaufoy’s Observations—All the preceding series of observations were 
* Observations made at the Magnetical and Meteorological Observatory at Toronto, in Canada, 
edited by Lt. Col. E. Sasryz, vol]. i. p. xii; vol. ii p. 10. 05 has been added to the yearly mean 
ranges from July 1, 1841, to June 1, 1842, derived from two-hourly observations, to reduce to hourly 
observations made afterwards. 
+- Observations, &c., at Hobarton, edited by Lt. Col. E. Sasrns, vol. i. p. xxvi. : 
{ Observations, &., at St Helena, edited by Lt. Col, E. Saprnz. For 1841-1845, see vol. i. p. 
24; for the remaining years the ranges are taken from the tables of hourly observations, vol. ii. 
§ Observations, &c., at the Cape of Good Hope, edited by Lt. Col. E. Saprnz, vol. i. p. xvi. 
From April to September 1841, the observations were two-hourly, afterwards they were hourly. 
Corrections of +0°55,+0"08,+0"61, and +049, have been applied to the mean ranges, for the 
months of April, May, June, and August 1841 respectively, on account of the observations wanting at 
the hour of minimum. 
|| This epoch is confirmed very nearly by the Milan observations. ScHIAPARELLI’s table of the mean 
diurnal ranges, from 1836 to 1873, given in his memoir, “Il periodo undecennali,” &c., has 
come to my knowledge only after this paper was written ; they confirm very nearly the epochs obtained 
from other observations. 


