Engelmann on Double Stars. 141 



motion may be clearly recognized. — e 3 , 2" , 455. 142°' 7 

 (1864-45).— Denib., 2"-479. 143°-97 (1863-09).— Secchi, 

 2"-576. 148°-4 (1856-06). — Struve, 2"-573, 155°-17 

 (1831-44). Movement in both, senses is still more evident 

 here. The 9'5 mag. star keeps its relative position. 



59. ^ Gygni. Stationary; if the angle is not very slowly 

 decreasing. 



104. 7 Leonis. 3»-387. 112°-93 (1864-31).— Demb., 

 2"-857. 109°-29 (1863-28). The results of different ob- 

 servers are still discordant, and the period must be very 

 uncertain. 



106. £ Ursce Majoris. 2"-568. 95°-42 (1864-2).— Demb., 

 2"-557. 96°-66 (1863-23). The distance appears to be 

 again decreasing since Seeches measure, 1857*357. 



1 112. 72 P. H. Gassiopece (c of Eng.). A and B, 2""38. 

 267°-4 (1864-93).— Demb., l"-927. " 265°-87 (1862-99). 

 Here Engelmamr's measure (of a single night) is much less satis- 

 factory than Denibowskr's, reversing the diminution of the 

 angle (as to which there is little doubt), and giving rather a 

 jump to the distance. 



Dr. Engelmamr's mean values have always been cited. 

 But it ought to be stated that, with the exception of Castor 

 and £ JJrsoe Maj., they are drawn from very few observations, 

 and those not always very accordant ; not unfrequently exhi- 

 biting only the result of a single night. And how liable such, 

 results are to further correction, all star-measurers know. 

 Denibowskr's have greatly the advantage in being deduced from 

 a much, larger number of observations. Still, every contri- 

 bution is of value, and it is evident that truth will only be 

 attainable through the means of a great amount of evidence, 

 some of which must be expected to be of a conflicting cha- 

 racter. Of this we have full proof in the recent observations 

 at the Radcliffe Observatory, Oxford. It has been announced 

 as the result of an examination, in 1863, of many of the stars 

 in the Dorpat Catalogue, that they do not exhibit that degree 

 of motion which Struve had concluded and anticipated. De- 

 duced by means of a heliometer, the largest, or one of the 

 largest in tlie world, and sustained by the prestige of a Green- 

 wich reputation, the Oxford observations have a strong claim 

 to be heard ; and England loves fair play. But Struve has, 

 and will have his supporters ; and it is obvious that the matter 

 ought to be fully gone into. That very considerable dis- 

 crepancies exist is well known to all who search into the 

 records of Double Star observations. But we have no right 

 to wonder at the fact, when we consider that \" of arc is a 

 very large value in these inquiries, and yet that quantity 

 would be represented by about ToVo"^ of an inch in the focus 



