485 
Mr. Ivory on the astronomical refractions. 
Example I. 
S = 86° 14' 42" 
Therm. 8°. 7 5 Cent. — 47°^ Fahr. 
Barom. o m . y^i = 29.17 In. 
Example II. 
6 =86° 15' 20" 
Therm. 8°^=46°.9 Fahr. 
Barom. o m .y66 = 30.16 In. 
86° io' 2.86325 
4 42" 662 
86° 10' 2.86325 
5 20° 752 
2.86987 
Therm. 0.00204 
Barom. 9.98781 1 0 
+ 9 } 9-98790 
2.87077 
Therm. - - 0.00281 
Barom. 0.00232 1 
+ 13) °‘° 024S 
Log. r 2.85981 
r — 724.1 = 12' 4'. 1 
— 0.28 x — 2| +0.6 
+ 0.8 x — 0.45 — 0.4 
Log. r - - 2.87603 
r = 751.7 = 12' 31". 7 
— 0.28 x — 3 = + 0.8 
— 0.16 x — °- 45 = +0.1 
12 4.3 
By observation 12 4.2 
12 32.6 
By observation 12 32.5 
Error 4 0.1 
Error of French T. 2.2 
Error + 0.1 
Error of French T. 2.9 
The next instance is more to the purpose, being the mean 
of 42 sub-polar observations of a. Lyras by Dr. Brinkley.* 
6 = 87° 42' 10" 
Therm. 35 0 
Barom. 29.5 
87° 40' 3-00466 
2 10" 39 o 
3.00856 
Therm. - - 0.01379 
Barom. 9.992701 
+ 64/ 9 ' 99334 _ 
Log. r 0.01569 
r= 1036.8 = 17' i6".8 
— 0.6 x — 15 + 9 o 
— 1 x 0.5 — o .5 
By observation 
Error - 
Error of French Tables 
17 25.3 
17 26.5 
1.2 
5-5 
* See his Paper on the Refractions, Irish Transact. 1815. 
