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

2 on the side of the Atlantic, and 30g 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.

Correction in Feet.

For Refraction.

For Curvature

and Refraction.

Correction in Feet.

700 01172 00167 01005 | 7.00051100073 00438 5 20.1769 2.8824 17.2945

7.500586 0008400502 6
8.00066700095 00572
8.500753 0010800645

6
7

24-0120 3.4303 20.5817 28.1809 4.0258 24.1551 32-6830 4.6690 28-0143

7.7181 46.3089

8.5996 51.5975

57-1714

750 01345 00192 01153 800 01531 00219 01312 850 01728 00247 01481 90001938 00277 01661 9.0 00844 00121 00723 737-5190 5.3599 32-1591 950 02159 00308 01851 9.50094000134 00806 8 42.6880 6.0997 36.5883 100002392 00333 02059 10-001042 00149 00893 8 48.1910 6.8844 41.3066 105002638 00377 02261 10.501149 00164 00985 54.0270 1100 0289500414 02481 11.001261 00180 01081 9 11500316400452 02712 11.5 01378 00197 01181 10 1200 03445 00492 02953 12.001501 00214 01287 11 1250 0373800534 03204 12.5 01628 00233 01395 12 1300 0404300578 03465 13-0 01761 00252 01509 13 13500436100623 03738 13.501899 00271 01628 14 140004689 00670 04019 14.002043 00292 01751 15 14500503000719 04311 14.502191 00313 01878 16 1500 0538300769 04614 15.0 02345 00335 02010 17 155005748 00821 04927 15.5 02504 00358 02146 18 160006125 00875 05250 16.0 02668 00381 02287 19 165006514 0093105583 16.5 02837 00405 02432 20 170006914 0098805926 17.00301200430 02582 1750 07327 01047 06280 17.5 03192 00456 02736 1800 077520110706645 18.00337700482 02895 1850 08188 01170 07018 18.503567 00509 03058 190008637 01234 07403 19.003762 0053703225 195009098 01300 07798 19.5 039630056603397 200009570 0136708203 20-0 04169 00596 03573

60-1971 66.7000 9.5286 80-7070 11.5296 69.1774 96.0480 13.7211 82.3269 112-7230 16-1033 96-6197 130-7320 18-6760 112.0560 150-0750 21.4393 128.6357 170-7520 24-3931 146.3589 192-7630 27.5376 165.2254 216-1086 30-8727 185-2359 240-7870 34-3981 206.3889 266-8000 38.1143 228-6857

and Refraction.

TABLE XVII.

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

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."