196 
POPULAR SCIENCE REVIEW. 
light, notwithstanding its faintness when dispersed), the other giving a spec- 
trum of bright lines, of which far the brightest is either the line “1474'” 
of Kirchhoff’s scale, or very close indeed to it. This line is seen in the 
spectrum’of iron, and appears in the spectrum of the aurora. Professor 
Young had long since mentioned reasons for believing that it belongs to a 
new element, and this view has lately been adopted by Mr. Lockver. 
On the strength of observations made during the eclipse Father Secchi 
expresses the assurance that the chromosphere is not a solar atmosphere, 
but made up of many relatively minute prominences. 
Sun-Spot Observations at Kew . — The following summary of sun-spot 
observations made at Kew has been communicated to the Royal Astrono- 
mical Society by Messrs. De la Rue, Stewart, and Loewy. 
Days Number of 
Months. 
January 
Days of 
observation. 
. 11 
without 
spots. 
0 
new 
groups. 
17 
February 
. 12 
0 
26 
March . 
. 14 
0 
31 
April . 
. 22 
0 
31 
May 
. 25 
0 
40 
June 
. 19 
0 
39 
July . . . 
. 18 
0 
36 
August 
. 25 
0 
44 
September . 
. 21 
0 
31 
October 
. 18 
0 
39 
November . 
. 17 
0 
22 
December 
. 11 
0 
37 
Total 
. 213 
0 
403 
■ remarked that the year 
1870 
11 was characterised by 
an exuberance 
solar energy which is without parallel since the beginning of systematic 
observations (i.e. since 1825). The number of observed groups far exceeds 
that in any previous year ; and it appears also from a cursory comparison 
with the maximum years’ observations, as recorded by Hofrath Schwabe, 
that the magnitude of the different groups, as well as the average amount of 
spotted surface during any period of the year, is unprecedented.” As the 
latter half of the year shows an increase of no less than thirty-five groups 
over the first half it seems likely that the maximum has not yet been passed, 
even if it has been reached. u A very remarkable feature of the groups 
observed during the year,” adds the report, u appears to be their remarkable 
lifetime There can be no doubt, from the observations, that an ex- 
ceedingly large number of groups completed three, four, and even more 
revolutions before finally collapsing. Whether this peculiarity in the be- 
haviour of groups belongs to all maximum years — whether the groups in 
minimum years are, on the whole, of a more ephemeral existence — and, fur- 
ther, in what manner the duration of any single group is connected with or 
dependent on its magnitude and the law of periodicity, are questions very 
forcibly suggested by the observations of the past year.” 
Notes on the Floor of Plato. — Mr. Birt continues his collection of obser- 
vations on the floor of Plato. He considers it not impossible that the 
