326 
POPULAR SCIENCE REVIEW. 
Palling stars in one hour. 
Date. 
Schmidt. 
Tupman. 
Denning. 
6 
August. 
6 
36 
13 
7 
» 
11 
37 
23 
8 
n 
15 
45 
26 
9 
29 
— 
44 
(max.) 10 
31 
59 
71 
11 
19 
53 
38 
12 
7 
27 
24 
Schmidt’s figures are very small and much below the num- 
bers found in recent years. But the averages in the table are 
not thoroughly reliable, inasmuch as they are based upon only 
a few years’ observations. A longer series might give a closer 
comparison, but it is seldom that the results of independent 
observers agree within small limits. There are differences in 
vision, modes of observation, and in position, which must 
obviously affect the numbers to no small degree ; and the inter- 
mittent character of the meteor shower itself must give rise to 
discrepancies which cannot at first sight be accounted for. The 
horary number of meteors on August 10 may vary, according 
to Heis, from 160 (in 1839) to 24 (in 1867). During the last 
ten years the writer has found little variation in the intensity 
of the annual returns when the conditions of weather and moon- 
light are fully taken into account ; and there is no question that 
some of the variations ascribed to the shower have no real 
existence, but are to be explained by the differences referred to 
above. 
A fair comparison cannot be instituted between the horary 
numbers found by observers, unless the observations, from which 
the values are deduced, are made, in each case, at similar hours of 
the night ; for shooting stars, though often plentiful after mid- 
night, are comparatively scarce in the evening hours. This is 
readily explained by the fact that the principal radiant points of 
the showers are massed together in the eastern region of the sky 
where the Earth’s orbital motion is directed, and it is obvious I 
that in the evening hours, when the altitude of many of them 
is very low, and when others have scarcely appeared above I 
the horizon, their operation is in a great measure restricted, 
so that only a feeble indication of their displays is per- 
ceptible at such a time. The case is entirely different at a 
later period of the night, when the constellations in which 
the several radiant points are situated have ascended high in 
the sky, and are in fact so placed that they may be seen to 
the greatest advantage. The August Perseids are always best 
observable in the morning hours, for the radiant point is very 
low on the horizon soon after dark, and a person who per- 
sistently watches it during the night, will find, with increasing 
