In Table XVI. of Mr. Baily, the Equation of equal Altitudes is given for the entire

interval of 24 hours, but it is seldom required beyond the above limits.

R

TABLE XV.

LENGTH OF A SECOND OF LATITUDE AND LONGITUDE IN FEET ON THE SURFACE OF THE EARTH, THE COMPRESSION BEING TAKEN AS 300.

Puissant, calculating the compression from the measurement of the great arc in France, obtains different results on different sides of the Meridian of Paris, making it as low as

309

250 on the side of the Atlantic, and to the Eastward; which latter quantity is generally assumed on the Continent.

TABLE XVI.

CORRECTIONS FOR CURVATURE AND REFRACTION.

Showing the difference of the Apparent and True Level in Feet, and Decimal parts of Feet, for Distances in Feet, Chains, and Miles.

For Refraction.

For Curvature

and Refraction.

3

6.0030

.8561

5.1469

8.1708 1.1673

7.0035

1.5246

9.1474

11.5773

40000383 0005500328 40 00167 00024 00143 21 4.1688

4.5002110003000181

50 00261 0003700224 34
5.500315.00045 00270 4
6.000375 00054 00321 4
6.50044000063 00377 5
70 005110007300438 5
7.50058600084 00502 6
8.00066700095 00572 6
8.500753 0010800645

7

14.2929

10.6720
13.5468 1.9295
16.6750 2.3821
20.1769 2.8824 17-2945
24.0120 3.4303 20-5817
28.1809 4.0258 24.1551
32-6830 4.6690 28-0143

450 00484 0006900415 500 00598 00085 00513 55000724 0010300621 6000086100123 00738 650 0101000144 00866 700 01172 00167 01005 750 01345 00192 01153 800 0153100219 01312 850 0172800247 01481 900 01938 00277 01661 9-0 00844 0012100723 7 37-5190 5.3599 32-1591 950 02159 0030801851 9.5 0094000134 00806 42.6880 6.0997 36-5883 1000 0239200333 02059 10-001042 00149 00893 8 48-1910 6.8844 41.3066 1050 02638 00377 02261 10.501149 00164 00985 9 54-0270 7.7181 46.3089 11000289500414 02481 (11-001261 00180 01081 9 60-1971 8.5996 51.5975 115003164 00452 02712 115 01378 00197 01181 10 66.7000 9.5286 57-1714 1200 03445 00492 02953 12.00150100214 01287 11 80-7070 11.5296 69.1774 1250 03738 0053403204 12.5 016280023301395 12 96.0480 13.7211 82.3269 1300040430057803465 13.00176100252 01509 13 112-7230 16-1033 96.6197 1350 043610062303738 13.501899 00271 01628 14 130-7320 18-6760 112-0560 14000468900670 04019 14.002043 00292 01751 15 150-0750 21.4393 128.6357 14500503000719 04311 14.5 0219100313 01878 16 170-7520 24.3931 146.3589 15000538300769 04614 15.002345 00335 02010 17 192-7630 27.5376 165-2254 1550 05748 00821 04927 15.5 02504 00358 02146 18 216-1086 30-8727 185.2359 16000612500875 05250 16.0 02668 00381 02287 19 240-7870 34-3981 206-3889 1650065140093105583 16.5 02837 00405 02432 20 266.8000 38-1143 228.6857 1700069140098805926 17.00301200430 02582 1750 07327 01047 06280 17.5031920045602736 1800 07752 0110706645 18.00337700482 02895 1850 081880117007018 18.503567 0050903058 1900086370123407403 19003762 0053703225 195009098 01300 07798 19:5039630056603397 20000957001367 08203 20-0041690059603573

and Refraction.

TABLE XVII.

REDUCTION IN LINKS AND DECIMALS UPON EACH CHAIN'S LENGTH FOR THE FOLLOWING VERTICAL ANGLES.

TABLE XIX.

COMPARATIVE SCALE OF FAHRENHEIT'S, REAUMUR'S, AND THE CENTESIMAL THERMOMETERS.

Fah. Reau. Cent.

Fah. Reau. Cent. Fah. Reau. Cent. Fah. Reau. Cent.

The following formula will serve for the comparison of these Thermometers.

The Logarithms answering to every degree of the graduations of the above Thermometers will be found at page 296, vol. i., of Dr. Pearson's "Practical Astronomy."