EXPLANATION OF TABLES 7 
TABLE 20.—PARALLAX OF SUN. 
This table contains the sun’s parallax in altitude computed by the formula: 
par.=sin 2 8/’.75, 
in which z=apparent zenith distance, the sun’s horizontal parallax being 8/’.75. 
It is explained in Chapter X. 
TABLE 21.—PARALLAX OF PLANET. 
Parallax in altitude of a planet is found by entering at the top with the planet’s horizontal paral- 
lax, and at the side with the altitude. 
TABLE 22.—MEAN REFRACTION. 
This table gives the refraction, reduced from Bessel’s tables, for a mean atmospheric condition 
in which the barometer is 30.00 inches, and thermometer 50° Fahr. 
TABLE 23.—MEAN REFRACTION AND PARALLAX OF SUN. 
This table contains the correction to be applied to the sun’s apparent altitude for mean refraction 
and parallax, being a combination of the quantities for the altitudes given in Tables 20 and 22. 
TABLES 24, 25.—CORRECTIONS OF REFRACTION FOR BAROMETER AND 
THERMOMETER. 
These are deduced from Bessel’s tables. The method of their employment will be evident. 
TABLE 26.—REDUCTION FOR MOON’S TRANSIT. 
This table was computed by proportioning the daily variation of the time of the moon’s passing 
the meridian. 
The numbers taken from the table are to be added to the Greenwich time of moon’s transit in 
west longitude, but subtracted in east longitude. 
TABLE 27.—AMPLITUDES. 
This table contains amplitudes of heavenly bodies, at rising and setting, for various latitudes and 
declinations computed by the formula: 
sin amp.=sec. Lat. sin dec. 
It is entered with the declination at the top and the latitude at the side. 
Its use is explained in Chapter XIII. 
TABLE 28.—CORRECTION FOR AMPLITUDES OBSERVED ON THE APPARENT 
HORIZON. 
This table gives a correction to be applied to the observed amplitude to counteract the vertical 
displacement due to refraction, parallax, and dip, when the body is observed with its center in the 
visible horizon. 
The correction is to be applied for the sun, a planet or a star, as follows: 
At Rising in N. Lat. 
Setting in S. Lat. 
At Rising in 8. Lat. 
Setting in N. Lat. 
For the moon, apply half the correction in the contrary manner. 
\apply the correction to the right. 
\ apply the correction to the left. 
TABLE 29._CHANGE OF ALTITUDE IN ONE MINUTE FROM MERIDIAN. 
This table gives the variation of the altitude of any heavenly body, for one minute of time from 
meridian passage, for latitudes up to 60°, declinations to 63°, and altitudes between 6° and 86°. Itis 
based upon the method set forth in Chapter XI under “Reduction to the Meridian” and the values 
may be computed by the formula: ; 
1’’.9635 cos L cos d 
sin (L—d) 
where a=variation of altitude in one minute from meridian, 
L=latitude, and 4 E 
d=declination—positive for same name and negative for opposite name to latitude at upper 
transit, and negative for same name at lower transit. 
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