T. S. Hunt—Celestial Chemistry. 123 
ing those terms which complete their period in less than eight 
An approximate knowledge of the epoch of the maximum 
or minimum temperature, will, for each of them, enable us to 
add an additional constant to the formula with a good degree 
of approach to the truth. 
6. The mean epochs of maximum or minimum can seldom 
be determined with precision even by employing the highest 
refinements of observation and calculation known to science. 
Indeed it appears unlikely that they ever have been ascer- 
tained for any points of the earth’s surface with less uncer- 
tainty than several minutes. It is moreover questionable 
whether there are any such epochs sufficiently marked to per- 
mit determinations without the introduction of various condi- 
tions; unless by the employment of observations extending 
over a series of years sufficiently long to eliminate all the vari- 
ety of conditions. Even if this be possible it will not be 
within the attainment of the present generation or their near 
posterity. 
Art. XI.—Celestial Chemistry from the Time of Newton; by 
T. Srerry Hunt, LL.D., F.R.S.* 
has, I think, scarcely been quoted, except r. Young, and 
Its existence is but little known, even among the best-informed 
scientific men. he essay in question was read before the 
esis of Newton was again printed in the L. H, and D. Philo- 
a Read before the Cambridge (England) Philosophical Society, November 28, 
1, and reprinted from its Proceedings. Z 
+ L. E. and D, Philos, Magazine, IIT, xxviii, 106 and 478; also xxix, 185. 
