120 
« The azimuthal velocity derived from M. Foucault's the- 
ory is expressed by the followmg equation: 
— =hAsind, (1) 
in which 4 denotes the azimuth measured from the north 
towards the east ; & the angular velocity of the earth, 7. e. 15° 
per hour ; and ) the latitude of the place of observation. This 
expression indicates a uniform angular velocity, and a time of 
revolution equal 24" x cosec. of latitude, which for Dublin 
would be about 29* 50”. 
“ The following Table, No. I., contains the mean results 
of the six experiments, giving the azimuth measured from N. 
to E., and the mean hourly motion, during the successive 
hours of observation : 
Tasxe I. 
No. of Ex- 
Hour. | Hourly Motion. Azimuth. periments. 
12°86° 12°86° 
11:90 24°76 
11°61 36°37 
11-50 47°87 
11-72 59°69 
10°82 70°41 
9°85 79°46 
10°77 90:23 
13-00 103°30 
11:47 114-77 
13°94 12871 
15:99 144-70 
14:32 159:02 
12°42 171-44 
6:96 178-40 
16:97 19537 . 
10°40 205°77 
12°38 21815 
11:01 229°16 
12°15 241°31 
6 
6 
6 
5 
5 
4 
4 
4 
6 
6 
4 
4 
4 
5 
5 
4 
3 
3 
3 
2 
