of Natural Philosophy. 153 
ts partial illumination during a central eclipse. Were Dr. 
wD S$ assumption concerning the amount of atmospheric 1e- 
fraction correct, his conclusion would not foliow; for the 
same agency of the atmosphere which produces twilight 
to an observer stationed on the earth’s surface, will produée 
the same effect to a second spectator, 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 
analy of the moon is concerned, is, that light is not given 
in any sensible degree from the crescent mene is unen- 
ightened by the sun, eet before and after opposit 
tempt to remove an objection tenths san’ ein 
inhabited by supposing io “heat is produced 4 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 bighly of astronomical science, to — 
have been suppressed. They are too far behind the pres- 
ent state of ‘Che hemistry, and too little essential to the ohieet 
which their author had in view, to deserve transcribing in 
the pages of an elementary work, which is intended to be 
employed in instruction. 
In passing to the Appendix,—our limits will not stew 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 ~ 
ve been advantageously corrected from those of 3 
bre and Burck khardt.—But the most important posi 
In Ewisee Astronomy and all the editions of Fatt ox: 
ney the tatty. 5 sags have given over the Bit table, rg. 4 
i Hence Pa taal whie sascha soe light trsiesait tothe 
moon's disc during a total eclipse to. ‘‘the reflection of rays of i 
=. the eartlr kinare ou ‘is doubtless in part « 0 
