154 
SCIENCE. 
The shower was observed by the writer this year on 
the evenings of the 8th and 9th (the sky being unfor- 
tunately overcast on the 10th and nth), and the dis- 
play found to be a feeble one. 
A three-hours’ watch on the 8th, from 9 to i2h., 
revealed 37 meteors. Of these, 16 were Perseids, 
giving as an hourly rate of Perseids (allowing for time 
spent in registering such tracks as were well observed) 
6, and for all meteors 14. 
The following table shows the number of meteors 
recorded each hour on the 8th during the watch, and 
also the calculated horary number for one observer 
looking towards the East: 
Duration 
of 
Watch. 
Length of Watch. 
No. of Meteors 
seen. 
Perseids. 
Calculated 
Horary No. 
State 
of 
Sky. 
All 
Meteors. 
Perseids. 
From 
To 
h. m. 
9 0 
10 0 
11 0 
h. m. 
10 0 
11 0 
12 0 
h. 
1 
1 
1 
9 
11 
*7 
6 
3 
7 
10 
13 
20 
7 
4 
8 
Very 
Clear. 
9 
i2h. 
3h. 
37 
16 
14 
6 
The magnitude of those recorded were as follows : 
= 2-C > iMag.*=iMag. = 2Mag.=3Mag. =4 and fainter. Total. 
Perseids 1 1 362 3 = 16 
Others o o 2 4 6 9 = 21 
Total 1 1 5 10 8 12 = 37 
The radiant point of the Perseids was deduced as 
at R. A. 38° +56°. Two showers in Cepheus furnished 
the majority of the uncorformable meteors recorded, 
their deduced positions being at R. A. 5°+7s° and 
R. A, 332°4-6o°. The evening of the 9th was generally 
clear (a few clouds at times but slightly interfering 
with the observations), and a watch of four hours, 
from 9 to 13L, was sustained, 91 meteors being re- 
corded. Of these, 54 or 59.4 per cent, were Per- 
seids, 12 or 13 per cent. Cassiopeids, and 25 or 27.3 
per cent, belonged to feebler showers in Andromeda, 
etc. 
The number recorded each half hour, and the cal- 
culated horary number, were as follows: • 
Duration 
of 
A 
OJ 
£ 
u 
0 
«u 
4 ) . 
9 
2 
Calculated 
Horary No. 
State 
of 
Watch. 
rC 
'o 1/1 
3 
'C 
<u 
a 
.2 
All 
Perseids. 
Sky. 
From 
To 
c 
>2 ■ 
o’ 
S3 
4 > 
a 
s 
u 
Meteors. 
h. m. 
9 0 
9 3 ° 
10 0 
10 30 
11 0 
11 30 
12 0 
12 30 
h. m. 
9 30 
10 0 
10 30 
11 0 
11 30 
12 0 
12 30 
13 0 
m. 
30 
44 
4 k 
44 
4 » 
41 
44 
9 
10 
10 
11 
14 
*5 
11 
11 
5 
8 
6 
7 
10 
7 
5 
6 
2 
0 
3 
2 
2 
2 
1 
0 
22 
24 
25 
26 
35 
37 
26 
26 
12 
19 
14 
16 
23 
16 
12 
14 
Clear. 
FewCl’ds. 
Clear. 
FewCl’ds. 
Clear. 
9 
i 3 h. 
4 h. 
9 * 
54 
(2 
28 
16 
Meteors thus appeared thickest between n and 
i2h., when the hourly rate for all meteors was about 
36, and of Perseids 20. The shower in Cassiopeia 
appears of considerable intensity, and probably the 
confounding of these meteors (Cassiopeids) with the 
true Perseids (the two radiants lying approximately 
near one another) may account for the large hourly 
rate of meteors being recorded as belonging to the 
Perseids by ordinary and occasional observers not dis- 
criminating enough, or who are not aware that two 
distinct showers exist in this region of the sky. The 
magnitude of those recorded on the 9th were as 
follows : 
“ 1 [ or $ > iMag.*=iMag. = 2Mag. = 3Mag. = 4 and fainter. Total. 
Perseids... 4 5 8 13 9 15 = 54 
Others-—- 1 o 4 27 23 = 37 
Total 5 5 12 15 16 38 = 91 
The radiant point of the main Perseid stream was 
very accurately deduced from several very short tracks 
near the focus, and from one perfectly stationary me- 
teor of the 1 st mag., visible two seconds and very ex- 
actly noted, as at R. A. 44^"° + 56^°. A secondary 
Perseid radiant was reduced from a few short tracks, 
and one very nearly stationary meteor, as at R. A. 
55° + 57°. Among the bright meteors recorded was 
one at 12E 55m., which equalled 9 (Venus) in 
brightness, and was of a blue color, with path from 
R. A. 26 o°+ 67^° to 212 0 + 66°. This meteor came from 
the direction of Cygnus. A letter received from Mr. 
W. F. Denning, F. R. A. S., of Bristol, England, in- 
forms the writer that the shower was well observed in 
England. Mr. Denning at Bristol recorded from 
August 6 to 13, inclusive, 419 t during a period of 
i6£h. watching, and of these 240 were Perseids. He 
found the hourly rate of all meteors on the 9th to be 
44, and of Perseids 28. On the 10th (when it was 
foggy) 34 and 28, respectively. The radiant point 
appeared to shift in R. A. (increasing) every night, 
for while on August 6 it was at R. A. 38°-t-56° and Au- 
gust 7-8 at R. A. 4i 0 -+55 0 , it was at R. A. 48° +57° on 
August 11-12, and at R. A. 4 g} 4 ° + S 7 'A° on August 
13 th. The meteors were also successfully observed 
at the Royal Observatory, Greenwich, where the greatest 
hourly number on the 10th was determined to be 
about 25, and also by Major Tupman, Mr. Corder, 
and other prominent observers. 
Cambridgeport, Sept. 12, 1880. 
AMERICAN ASSOCIATION FOR THE AD- 
VANCEMENT OF SCIENCE, 1880. 
( Continuation of papers read. ) 
NOTES ON JAPANESE PULMONIFERA. 
By Prof. Edw. S. Morse. 
In this communication Mr. Morse called attention to the 
occurrence of a number of species of land snails in Yeso, 
identical with forms occurring in New England. 
He also showed the occurrence of two species of slugs 
in Japan, which are also common in New England. 
While he had met with most of the fresh water genera of 
Pulmonifera in Japan, he had never yet found an example 
of Physa. 
PROBLEMS IN WATSON’S CO-ORDINATES. 
By Thomas Hill, D.D., LL.D. 
In this paper Dr. Hill investigates the equation p=A (a — 
bSin. ra») n [giving his principal attention to the case in which 
b=m = i, and n= — 1, which represents a curve like a figure 
8 with its top concave, somewhat like the sign for Taurus. 
When a=o, this becomes a parabola; and when a>2, an 
