618 
PEOEESSOE EOSCOE ON A METHOD OF METEOEOLOGICAL 
Simultaneous Measurements with Pendulum Instrument and New Photometer. 
April 29th, 1864. 
May 10 th, 1864. 
Time. 
Intensity. 
Difference. 
Time. 
Intensity. 
Difference. 
Pendulum 
instrument. 
New photometer. 
Pendulum 
instrument. 
New photometer. 
h m 
9 30 a.m. 
10 0 
11 0 
11 5 
12 30 p.m. 
12 32 
1 30 
2 0 
2 30 
3 0 
3 0 
3 30 
0-210 
0-160 
0-073 
0-064 
0-200 
0-210 
0-068 
0-105 
0-124 
0-136 
0-117 
0-157 
0-180 
0-160 
0-083 
0-078 
0-210 
0-220 
{!«}“ 4 
0-105 
J 0*1331 
[ 0-133 j 
0-144 
0-114 
0-182 
-0-03 
0-00 
+ 0-010 
+ 0-014 
-0-01 
+ 0-01 
-0-04 
0-00 
+ 0-009 
+ 0-008 
— 0-003 
+ 0-025 
h m 
9 0 A.M. 
10 0 
11 15 
12 30 p.m. 
1 1 0 
2 30 
2 33 
4 30 
0-093 
0-100 
0-130 
0-220 
0-100 
0-105 
0-115 
0-0125 
{S2}«» 
0-110 
0-150 
0-250 
f 0 09 9l o-lOO 
\ 0-102 J u luu 
/ 0-109 1 Q.JQO 
1 0-096/ u 
0-116 
0-0106 
-0*011 
+ 0-010 
+ 0-020 
+ 0-030 
0-000 
—0-003 
+ 0-001 
-0-002 
Simultaneous Measurements (continued). 
June 8, 1864. 
Intensity. 
Time. 
Pendulum 
New 
Difference. 
Time. 
photometer. 
instrument. 
h m 
h m 
10 40 A.M. 
0-229 
0-203 
-0-026 
9 50 A.M. 
10 42 
0-232 
{ S } 0 ' 233 
+ 0-001 
10 25 
11 25 
0-218 
0-207 
-0-011 
10 40 
11 27 
0-225 
0-217 
-0-008 
1 33 p.m. 
0-205 
0-231 
+ 0-026 
2 15 
0-218 
0-230 
+ 0-012 
11 45 
2 17 
0-224 
0-233 
+ 0-009 
3 20 
0-072 
0-064 
-0-010 
3 22 
4 0 
0-077 
0-039 
0-068 
0-048 
-0-009 
+ 0-009 
12 15 p.m. 
4 3 
0-031 
0-036 
+ 0-005 
12 45 
1 30 
2 21 
2 46 
July 16, 1864. 
Intensity. 
Pendulum 
photometer. 
New 
instrument. 
Difference. 
{53} 
PP 
0-19 
°‘14 I ft - or 
0-13/ 0135 
{ 
{53} 
0-24 
0*16 
0-18 
0-20 
0*17 
h0*21 
0-17 
f 0*24') 
J 0*20 
0-19 
1 0-18 , 
h0-20 J 
f0-17' 
ft- 
^0-205 
0-145 
0 - 13^1 
III 
0-13 J 
0-00 
- 0-02 
+ 0-02 
+ 0-012 
-0-025 
+ 0-02 
+ 0-008 
The curves on figs. 7, 8, & 9, Plate XXVIII. exhibit these results graphically for the 
first three days, and a glance at these curves show how closely the measurements made 
