Dr. Pearson's Introduction to Practical Astronomy. 455 



structed. Tables XIV. and XV., giving the aspects, are of but little 

 use J they are, as our author observes, " more calculated to gratify 

 curiosity than to answer any useful purpose." 



The next set of Tables are termed Zodaical Tables, so called by 

 the author because they are applicable to those phaenomena which 

 occur in the zodiac, such as eclipses, occultations, &c. On this 

 account some Tables which, strictly speaking, ought to have appeared 

 among the Lunar Tables, find their plttce here ; such as the Tables 

 from XIII. to XXV. inclusive, relating to the moon's parallax in longitude 

 and latitude, in right ascension and declination. These Zodiacal 

 Tables extend from page 203 to page 261. The first is the converse 

 of the Solar Table V. or VIII., and is given for the purpose of obtaining 

 the sun's longitude from his right ascension. Tables II. and III. are 

 very laborious Tables, originally constructed by Dr. Maskelyne, but 

 here enlarged and improved by our author. Tables IV. and V. contain 

 corrections to be applied to the quantities determined by the pre- 

 ceding Tables, for a small variation in the obliquity. As one of the 

 principal uses of these Zodiacal Tables is to furnish the elements of 

 computation in the determination of the longitude from an occulta- 

 tion of the fixed stars, it is of importance to know what stars may be 

 occulted by the moon. Table VI. is introduced for this purpose, as 

 copied from the Jalirhicli of 1 7S0 ; but an enlarged one, in the order of 

 right ascension, is subsequently given in the Appendix (p. 5 15 — 528). 



As the longitude and altitude of the nonagesimal, or the highest 

 point of the ecliptic above the horizon, are requisite elements in the 

 determination of the moon's parallax in longitude and latitude, a Table 

 for facilitating these laborious computations by furnishing the above 

 elements must be of great use. For this purpose Table VII. has been 

 constructed. The angle of position is also another useful element on 

 •many occasions: the two Tables VIII. and IX. have been added by 

 our author for facilitating its computation for zodiacal stars. This 

 angle, with the latitude and longitude, enters into the formulae for 

 aberration, and is moreover an element in the computation of eclipses, 

 parallaxes, occultations, &c. Tables XI. and XII. are only modifi- 

 cations of the Solar Tables VI. and V. Table XIII., with its appen- 

 dix, is of more importance, as it furnishes us with an important ele- 

 ment in the computation of occultations of the fixed stai-s by the 

 moon. 



In the explanatory part of the work we find a few additional Tables 

 given ; the first is fof the correction of parallax in the spheroid, 

 computed from a formula given by Dr. Young. Following this are 

 six small Tables, the first of which gives the longitudes and latitudes 

 of Dr. Maskelyno's tliirty-five stars, and the rest relate to the correc- 

 tions of the mean longitudes and latitudes. 



After two Tables expre.ssing the lengths of circular arcs in terms 

 of radius, there follows in the proper order a collection of Planetary 

 Tables. The first six of these are for determining the parallaxes of 

 the planets. Tiic seventh ail'ords t he means of con verting tlie geocentric 

 liingitude of a planet into rigiit ascension. Then follow five more 



