ASTRONOMY, PROGRESS OP, IX 1893. 



45 





iniiin of acceleration should occur, after which 

 the interval* between tin- eelip.-es should begin 

 to 1, n^iln-11 until the passage of the useuinlinj,' 

 n<"!. in about 1934. 



Though only the principal star has ever been 

 seen, Algol is supposed to be a triple star. Dr. 

 Chandler has hope of the actual telescopic dis- 

 covery of the distant component, even if it is 

 only slightly luminous. Its position angle is 

 about ;;_' , and its distance about 2". 



Position of Solar Apex. A new deter- 

 mination of the direction of the sun's motion 

 has been made by Prof. J. G. Porter, Director of 

 the Cincinnati Observatory, who has availed 

 himself of the proper motions of 1,340 stars, pub- 

 lished in No. 12 of the "Transactions" of that 

 observatory. He divided the stars into four 

 groups, according to the amount of their annual 

 proper motion, and secured four determinations, 

 based ou the following data : 



Group I, 576 stars with proper motion less 

 than 0-3" ; Group II, 563 stars with proper mo- 

 tion between 0'3" and 0-6' ; Group III, 142 

 stars with proper motion between 0'6" and 1*2" ; 

 Group IV, 70 stars with proper* motion greater 

 than 1-2". 



He finds the direction of the sun's motion, 

 and, of course, that of all the circumsolar bodies, 

 to be toward : 



Prof. Vogel has published results based on 

 the measured velocities of 51 stars in the line of 

 sight, but the deduced position of the point 

 toward which the sun is moving is not in very 

 satisfactory accord with other investigations, 

 lie makes the co-ordinates of the apex in right 

 ascension 206-1 ; declination north 45-9 ; and 

 a velocity of 10'9 English miles a second. 

 Prof. Porter's position is about 3 northeast of 

 Alpha Lyra, while that of Prof. Vogel is in 

 Bobtes, about 4 southeast of Eta Ursae Majoris. 

 The place assigned to it by Sir William Her- 

 schel is in Hercules, about midway between 

 those of the preceding observers. Prof. Boss, of 

 the Dudley Observatory, at Albany, has com- 

 puted its position, using a different set of stars, 

 and locates it in Cygnus, longitude 289 ; de- 

 clination north 51. If, however, the neighbor- 

 ing stars, such as the bright stars of Ursa Major 

 and of Orion, be combined into groups, the posi- 

 tion of the apex is still farther from that gen- 

 erally assigned to it, viz. : Right ascension 

 159-7 ; declination north 50, or in Ursa Major ; 

 velocity per second, 8-11 miles. L. Struve places 

 the apex in 266-7 ; declination + 31, or in Her- 

 cules ; velocity, 7'69 miles. 



Where results are so discordant we can not be 

 certain regarding that point of the heavens 

 toward which the sun is moving. But, discrep- 

 ant as the computed positions of the solar apex 

 may be, there is remarkable agreement as to the 

 sun's velocity. 



Light Comparisons. Mr. Henry Parkhurst, 

 of Brooklyn, who for the past ten years has 

 made observations of the brightness of 36 aster- 



oids with a wedge photometer, says that when 

 the observations are corrected for phase ami re- 

 duced to unity of distance from both the sun 

 and t he earth, the results are remarkably accord- 

 ant, and he infers that the brightness of the sun 

 has not varied 1 per cent, during the ten years. 

 From these careful studies he thinks the aster- 

 oids are better standards for light comparisons 

 than the stars, as most of the latter are subject 

 to variation, while the former are exempt from 

 this uncertainty. 



Variation of Latitude. It has long been 

 suspected by astronomers when accurate obser- 

 vations for latitude have been undertaken that 

 this co-ordinate was subject to a slight variation, 

 but even its advocates little dreamed of the 

 periodicity of such change. In 1884-'85, Dr. Seth 

 C. Chandler, of Cambridge, Mass., after more 

 than a year's observations with his almucantar, 

 felt that not only was there possibility of varia- 

 tion of latitude, but also of some law governing 

 it. In following up his thought and the inves- 

 tigations of 1885, he later obtained observations 

 for latitude from Berlin, Prague, Potsdam, Pul- 

 kowa, and the Sandwich Islands, which con- 

 firmed his supposition of the change and its law. 

 He has shown positive evidence of a periodic 

 variation of the latitude caused by the rotation 

 of the geographical pole around the astronom- 

 ical pole in four hundred and twenty-seven days. 

 The deviation is very slight, the two polar cen- 

 ters being only about 27 feet apart. 



Dr. Chandler finds that a four hundred and 

 twenty-seven days' period accounts for the con- 

 tradictory results obtained from the above-named 

 observatories and from those from the Washing- 

 ton and Harvard College observatories. 



To make this abstruse subject as plain as pos- 

 sible, suppose at a given time all the observa- 

 tories of Europe should simultaneously show an 

 increase of latitude, which fact would indicate 

 that the equator had receded from Europe and 

 that the north pole had approached it. If at 

 the same time with this observed increase of 

 latitude in Europe the latitude of observatories 

 on the opposite side of the earth should lessen, 

 then it would be presumably certain that the 

 pole had receded. This is just what Dr. Chand- 

 ler tried to ascertain. After exhaustive analysis 

 of the reliable observations from all parts of the 

 world he has sufficient evidence to justify the 

 announcement that the pole of the earth does 

 actually revolve around the pole of the heavens. 



This fact may result in discrediting the cor- 

 rectness of the assumed values of stellar paral- 

 lax. Dr. Chandler's papers on the subject may 

 be found in Vols. XI and XII of Gould's " As- 

 tronomical Journal," Cambridge, Mass. 



Planetoids. Since the discovery of the last 

 asteroid given in the " Annual Cyclopaedia " for 

 1892 the finding of these troublesome bodies 

 has progressed rapidly, 44 having been found. 

 With a few exceptions' these were first detected 

 on photographic plates in the form of a short 

 trail caused by their orbital motions during the 

 time of exposure, after which they were observed 

 visually for identification and for position for 

 the computation of the elements of their orbits. 

 This, for various reasons, is attended with so 

 many uncertainties that, until all doubts are 

 removed, they are provisionally named by the 



