SEYFFARTH — ON THE THEORY OF THE MOOX S MOTIONS. 523 



The present theory of the moon's motions is deduced from the 

 unalterable law of gravitation ; consequently all other lunar theo- 

 ries essentially diftering from the present are to be rejected. To 

 this argument of professed astronomers I have, of course, to re- 

 spectfully submit. And yet, as a reminder, I venture to ofler 

 the following facts. Granted that Damoiseau's Tables, Airy's 

 corrections inclusive, are based upon the immutable law of gra- 

 vitation, including the influence of the planets, — how comes it to 

 pass that these Tables disagreed so much with the observation of 

 the total eclipse in 1851 ? How comes it that all the total eclipses 

 of the sun, verified by Greek and Roman historians, are partial 

 when computed by Damoiseau and Hansen's Tables? that, ac- 

 cording to the same Tables, many ascertained ancient eclipses 

 were invisible, that the latter preceded sunrise and the attested 

 hours of the day? How is the phenomenon to be explained that 

 the numberless Lunar Tahles, constructed successively from Ptol- 

 emy to Hansen, difter so much from each other concerning the 

 mean motions and the secular accelerations of the moon, her Ap- 

 sides and Nodes ; that, moreover, all these Tables, some years 

 after their construction, proved useless ? I refer to the statements 

 of the Tabulae Prudenicce, of Rudolph, Marinus, Pagan, La Hire, 

 Cassini, Clairaut, Halley, Mayer, Mason, Lalande, La Place, 

 Wurm, Buerg, Voiron, Burckhardt, Bouvoir, Euler, Damoiseau, 

 Hansteen, Airy, Hansen, which I compared with each other. 

 How is it that Buerg's Tables, based on 3200 Greenwich observa- 

 tions, agree much better with the eclipse in 1S51 than those of 

 Burckhardt? that Prof. Airy, being down to 1875 fully convinced 

 of the correctness of Hansen's theory, is just now occupied with 

 a new theory of the moon's motions ? 



It is not yet known what will result from the researches of this 

 distinguished astronomer. Should he, by a closer examination of 

 the planetary attractions, arrive at the result that in — 2300 the 

 longitude of the moon was shorter by about 6°, that of the Nodes 

 shorter by about iS°, that of the perigee nearly 8° shorter than 

 the usual Tables state, then he will be under the necessity of aban- 

 doning the eclipses in the Almagest, as I have done, since 1846, 

 in different places. On the other hand, should it be impractica- 

 ble, in this way, to explain the greatly accelerating motions of the 

 moon, as specified in our Table, p. 429, which is approximately 



