XXV 



Nathaniel Holmes, A.M., 



Corresp. Secretary of the Academy of Scietice, of St. JLoicis, Mo. 



Dear Sir: — My Chronology of the Ancient Eclipses, and approximate 

 Corrections of the actual Theory of the Moon's Motions, published in the 

 Transactions of our scientific Academy (vol. iii. pp. 401-530), being known, 

 it will interest you that a distinguished astronomer of our country is just 

 now occupied with constructing new Lunar Tables. Of course, since those 

 of Hansen, presumed to be correct for all time to come, commenced after 

 twenty years to disagree with the motions of the heavenly bodies, the re- 

 placing of them with better ones could not be deferred longer. It is Simon 

 Newcomb, Prof. U.S. Navy, who, at present, aims to establish finally per- 

 fect Lunar Tables, as we learn from his " Researches on the Motion of 

 the Moon, made at the U. S. Naval Observatory, Washington. Part I. — 

 Reduction and Discussion of Observations of the Moon before 1750. Wash- 

 ington, 1S78." In this very valuable work of 280 pages in quarto, the learned 

 author first specifies the auxiliaries by which he hopes to solve the great 

 problem. Concerning the latter, it is true. Prof. Newcomb recurs to a great 

 many observations, formerly unknown or totally forgotten; but, on the other 

 hand, he neglects the most important expedients, and relies on ancient 

 eclipses totally wrong. Since the matter is of great influence; since I have 

 discussed, though popularly, the same question in difterent works subse- 

 quent to my " Chronologia Sacra," and since my hand is responsible for 

 neglecting to warn against the propagation of scientific falsehoods, — your 

 love of science will certainly allow me to display the reasons which both 

 prevent me from believing that Prof. Newcomb will, in the usual way,, 

 accomplish the end, and convince me that his new Tables will, after twenty 

 years, turn out to contradict the observers as much as Damoiseau's Tables 

 did in A.D. 1S51, and those of Hansen in 1876. 



In the first place, the manuscript observations preserved in the observa- 

 tories of Paris, Luxemburg, Greenwich, Danzig, Petersburg, Pulkowa, 

 etc., and the observations of the Arabians of Cairo and Bagdad, are, as it 

 appears to me, too modern for fixing the places of the moon, her nodes 

 and apsides, on account of the Roman, Greek, Babylonian and Chinese 

 eclipses being 2,000, even 4,000, years older. Suppose those observations, 

 made from a.d. 700 to 1750 without chronometers and telescopes, to con- 

 tain defects of a few seconds concerning the times and magnitudes of the 

 respective eclipses, what then.^ — Since these trifling errors increase rapidly 

 backward according to the squares of times, it is evident that the aforesaid 

 rather modern observations are not at all adapted to fix the secular mean 

 motion of the moon, or her secular accelerations, since the epoch 3000 b.c. 



Further, all astronomers maintain that the accelerations of the moon, 

 her nodes and apsides, are periodical only, and that they are eff'ected by 

 the planets next to our globe, namely, by an unknown combined revolving 

 period of them. This long period, first discovered in my " Chronologia 

 Sacra," 1846, consists of 2146 Julian years, during which Saturn performed 

 74 revolutions, Jupiter 170, Mars 67 of 32 years each, Venus 268 of 8 years 



