of JVatiiral Philosophy. \5d 



its partial illumination during a central eclipse. Were Dr. 

 H.'s assumption concerning the amount of atmospheric le- 

 fraction correct, his conclusion would not follow ; for the 

 same agency of the atmosphere which produces hvilight 

 to an observer stationed on the earth's surface, will produce 

 the same effect to a second spectatoj", stationed any where 

 behind the first, and in the same tangent plane of the earth.* 

 Another obvious proof that Dr. H. was misled by his zeal 

 to find points of analogy between the sun and the other 

 bodies of the system, at least so far as the phosphorescent 

 quality of the moon is concerned, is, that light is not given 

 off in any sensible degree from the crescent which is unen- 

 lightened by the sun, just before and after opposition. 



The attempt to remove an objection to the sun's being 

 inliabited by supposing that " heat is produced by the sun's 

 rays only when they act on a calorific medium," and that 

 they are the cause of heat only " by uniting with the mat- 

 ter of fire which is contained in the substances that are 

 heated," together with the arguments advanced in support 

 of these strange positions, certainly ought, for the credit of 

 one who has deserved so highly of astronomical science, to 

 have been suppressed. They are too far behind the pres- 

 ent state of Chemistry, and too little essential to the object 

 which their author had in view, to deserve transcribing into 

 the pages of an elementary work, which is intended to be 

 employed in instruction. 



In passing to the Appendix, — our limits will not allow us 

 to notice a variety of errors which occur in the progress of 

 the examples; nor a number of small inaccuracies unne- 

 cessarily introduced into the mode of projecting solar 

 eclipses. The tables of epochs (which terminate with the 

 present year) should have been extended; and might also 

 have been advantageously corrected from those of Delam- 

 bre and Burckhardt. — But the most important positive er- 

 ror, perhaps, which occurs in the Appendix, relates to the 

 method of finding the arguments of the moon's latitude. 

 In Ewing's Astronomy and all the editions of Enfield ex- 

 cept the last, we have given over the Illd table, " Arg. I — 



* Hence the 93cl Proposition, wiiicli ascribes tiie light transmitted to the 

 moon's disc during; a total eclipse to " the rtjledion of rays of light falling 

 upon the earth's atmosphere," is doubtless in part carrect. 



Vol. Ill No. 1. 20 



