Astronomical and Nautical Collections. 101 
thirteenth number of these collections. Mr. Ivory not having pre- 
cisely assigned the temperature at which his tables may be sup- 
posed to represent the results of the exterior thermometer, the 
errors of the New Tables have been copied from his own comparison 
of these tables with Mr. Groombridge’s observations, and it is 
obvious that the New Tables, thus compared with the phenomena, do 
not at least possess any advantage over those of the Nautical Al- 
manac ; though they can scarcely be said to be decidedly inferior, 
with regard to the lower altitudes: but at 45° it appears to be 
highly improbable that the refraction, at the temperature of 50°, or 
even of 48°, can be so much as 57.36. 
. Professor Brssxx has given us, in the Berlin Almanac for 1826, 
the results of his latest observations on the refractions near the 
horizon, which show, very satisfactorily, what was. perfectly well 
known before, that his table is founded upon an inadequate theory, 
and that it is of no particular use where any correct theory at all is 
wanted. The comparative results of the different determinations 
may be exhibited in a short table. 
Comparative Results, Barometer 30. 
N.A. N. A. 
Alt. apn ai 5z° Int. Ivory Dift- Bessel F, A. tet Corr. 
oO / / “a , uw J Mu 7 ‘ “ v “ uN 
0 0 3351 33 34.8 34 17.5 +42.7 36 36.1 36 0 —36 
0 30 28 37 28 24.8 28 40.8 +16.0 29 51.4 29 27.3 —24.06 
1 0 2425 2415.6 2421.8 +6.2 24 58.2 24 44.6 —13.60 
1-30-21 7 20 59:2 20 59:6 +0.4 21 18.3 21° 7.9 —10.35 
2 0 1829 18 22.6 1819.6 —-3.0 18 28.8 18 23.3 -— 5.46 
230 1621 1615.6 16 10.89 —4.7 1615.1 1613.9 — 1.19 
8 0 14 35 14 80.4 14 26.04 —4.4 14 27.5 14 26.1. — 1:42 
830 18 7 18 3.0 12 59.51 —-3.5 1259.5 12 58.7 — 0.77 
4 0 11 52 11 48.6 11 47.15 —1.1 1146.4 11 48.4 + 1.97 
430 10 50 1046.9 10 46.03 —0.9 10 44.9 10 48.2 + 3.30 
5 0 958 955.2 9 583.84 —1.4 952.5 9 52.4 + 0.05 
6 0 8 82 829.7 8 29.80 +0.1 8 28.5 Berl. Astr. Jahrb. 
7.0. 227 7.25.0, .7 25.40 +0.4. |7 24.2 1826. 
8 0 635 683.3 6 34,68 +0.4. 6 33.6 
9 0 554 5.52.5. 5 58.79 +1.8 . 5 52.8 
10 0 520 518.6 520.19 +1.6 519.4 
15 0 8 34.8 8 93.4. 384.70 +1.3 8 84.3 
