192 
POPULAR SCIENCE REVIEW. 
Months 
Days of 
Observation 
Days without 
Sun-spots] 
Number of 
New Groups 
Numbers in 
the Kew Catalogue 
January 
14 
0 
15 
No. 902 
to 916 
February 
15 
0 
17 
917 
933 
March 
11 
0 
14 
934 
947 
April 
20 
0 
15 
948 
962 
May 
16 
0 
18 
963 
980 
June 
18 
0 
27 
981 
1007 
July 
22 
0 
18 
1008 
1025 
August 
19 
0 
25 
1026 
1050 
September 
21 
0 
21 
1051 
1071 
October 
18 
0 
17 
1072 
1088 
November 
1 11 
0 
15 
1089 
1103 
December 
11 
0 
22 
1104 
1125 
196 
1 
0 
224 
902 
to 1125 
There is a steady increase in the number of groups and the areas covered 
by them, a circumstance which points to the approaching maximum of the 
sun-spot period. The observers remark that the year was characterised by a 
remarkable tendency of the groups to appear in successive trains, within 
narrow and well-defined zones, on both sides of the solar equator. A regular 
successive appearance of spots along parallels of latitude had been previously 
observed, but it usually only lasted during a short period, after the lapse of 
which the distribution in latitude became again irregular. Last year the- 
irregularity of distribution was the exception. It is not improbable, the- 
observers add, that a distinct law may be traced at some future time in 
this singular behaviour, and they recommend the subject to the attention 
of observers. 
Professor Kirkwood on Sun-spot Periods . — This laborious and thoughtful 
astronomer has subjected Wolf’s periods to careful scrutiny, and has been 
led to the conclusion that in order to account for sun-spot periods we must 
suppose that portions of the sun lying in certain solar longitudes are more 
capable of being influenced by disturbing causes than other regions. He 
ascribes to Mercury the most powerful disturbing effect, and in particular he 
regards this planet as the cause of the 11-year period — 46 revolutions of 
Mercury being equal to 163 solar rotations, and to about 11^ years. 
Comets and Meteors . — The same astronomer shows reasons for believing 
that the solar system, as it passes through the interstellar spaces, traverses 
regions in which cometic or meteoric matter is sometimes densely and some- 
times sparsely strewn. He concludes that during the interval from 700 to 
1,200 the solar system was passing through or near a meteoric cloud of veiy 
great extent ; that from 1,200 to 1,700 it was traversing a region compara- 
tively destitute of such matter; and that about the commencement of the 
eighteenth century it again entered a similar nebula of unknown extent. He 
points to a fact which has not hitherto, so far as we know, been noticed, that 
all the comets whose perihelion distances are less than 001 have their 
perihelion close to the direction towards which the sun is moving, while 
those whose perihelion distances are less than (H)5 exhibit a well-marked 
approach to the same peculiarity of distribution. 
