The Montgomery advertiser., 1904-08-01

0hanIutaIX pIe elliptic laws which Kepler annaun- ced Iii was found that the planet was sonetimes in advance, sometimes a lit- tle in arrear of the calculated posit- ion. It was also discovered that the nath which the planet followed was not again exactly traversed during the next revolution. In fact, it was shown while the planet moved as Kerler said 1t did, yet that when we examined minuteIy the movements which were followed we found innumerable small departures from the simplicity of el- liptic motion. Such discrepancies are always of value in scientific investi- gatfon. We calculate what magni- tude is expected to be. and then we measure what Is actually presented to us. The difference between the two can only be regarded as an indication of the presence of some agent which was either overlooked or not accurat- ely allowed for in the process of mak- ing the calculation. The deviation in the places of the planets from those which would be taken by elliptic mot ion alone have been shown to arise from the mutual attraction between one planet and another. One after another these problems have all, or nearly all, yielded to the repeated att tacks of those astronomers who wield the potent weapons om mathematical analysis; their discoveries from some of the most striking chapters in the history of astronomy and they have a beautiful illustration of the great law of gravitation and confirm in a strik- ing manner the evidence on which our belief in that law is founded. The famous French mathematician, Lag range, has discovered certai beautiful principles in connection with the theory of planetary perturbation. He has shown that the extent to which the perturbation of one planet by the remaining planets can affect its mot ion is limited. This Is a proposition of singular interest, inasmuch as it in- wolves the stability of the planetary system. When first the dictum of per- turbatfon began to receive attention fears were sometimes entertained lest the irregularities of the earth's orbit should grow to such an extent as to re- suit in a total Reorganization of the condition of life. It was thought that the attraction of the great planets might ultimately draw the earth so far away from the sun as to render organic life on 1t impossible. Then, again, 1t was feared lest the sun would attract the earth to such a dangerous prox- unity as to render life impossible from excessive heat. To Lagrange. however, is due the merit of having explained how 1t is that perturbations have never been able, even in the millions of years to accumulate, fin the earths path changes so perilous. It has demon- strated that the incompetency of per- turbations to produce such disastrous effects changes in the planetry system Is confined within definite limits. The orbits are now nearly circular; they can never depart more than a certain extent from that form. The dimen- sions of those orbits as measured by the longest diameter remain unalterably planes of the orbits must always re- main in the vicinity of their present situation.
 Of the circumpolar cancellations Draco will be on the meridian at about o'clock in the August evenings It is characterized by long, winding line of stars. mostly small. extending halfway around the pole and separat- ing the two Bears. The head of the monster is easily distinguished by the four stars-Beta, Gamma. Zeta and Nu- from degrees to 5 degrees apart, so situated as to form a rather conspicuous quadrilateral. Alpha Dra- conis. or Thuban, Is in the tail of the Dragon, and for this reason is some- times called by mariners the Dra- gon's Tail. It is half-way between Gamma Ursae Minoris, in the bowl of the Little Dipper, and Zeta Ursae- Ma joris, or Mizar. the last but one in the handle of the Great Dipper. Thuban Is a remarkable star. for 1t has been found that about 4,000 years ago 1t was the pole-star, the present pole star being then fully 12 degrees dis tant from the pole of the heavens. It Is curious circumstance that cer- tain of the tunnels ;n the pyramids of Egypt face exactly to the north and slope at huch an inclination that this star at its lower continuation would have been visible from their lower end at the date when the pyramids are supposed to have been built. It is probable that these, passages were arranged to be used for the purpose of observing the transits of what then was the pole star.
 Not far from the Dragons Head we see one of the most brilliant stars in the heavens-Vega-in the constella- tion Lyra. On the east it Is attend ed by the two fourth magnitude stars Espilon and Zeta. At distance of about 8 degrees southeast from Vega are stars Beta and Gamma Lyrae. the
 former being a remarkable variable star that consists of two bodies, gas eous in their nature and revolving round each other SO near together as to be almost in contact. South of Lyra, in a somewhat easterly direc- ton, and east of Ophinchus is situated the rather conspicuous constellation Aquila, or the Eagle. whose character istic configuration is that formed by Alpha. or Altair. with Gamma to the north and Beta to the south. Between Aquila and Lyra, though nearer to the former. we see the little constellation Sagitta, or the Arrow one of the an- cient AS of Ptolemy. The two stars Alpha and Beta, which mark the feath- OF of thn arrnyu lie raaYlY midway be-