Progress of Astronomy during the Year 1879. 451 
almost parallel and equal in length to the line between 6 and ¢ 
_Cancri, joined to the small size of the improvised circles of the 
instrument, appears to him to prove beyond doubt that the 
objects seen were nothing but the stars @ and ¢ Cancri. The 
constant error of about 3", which under this supposition would 
affect the R. A.s of a and 6, he tries to explain by the different 
circumstances under which the circle markings were made for 
the stars and for the Sun; in the former case in semi-darkness 
and in a hurry, in the latter case in full daylight and with 
leisure ; possibly also the markings were made at the same side 
of the wire-pointer, thus creating a parallax of 3° or 3, of an 
inch. Mr. Swift’s observation is treated more summarily by 
Professor Peters, who thinks the confusion and_ successive 
eradations in his statements must deprive every reader of con- 
fidence in them. 
To this criticism Professor Watson has given an indignant 
reply, in No. 2263 of the same journal. He denies flatly that 
his wire-pointers were as easily bent as supposed by Professor 
Peters, and feels confident that the probable error of 5’, assigned 
by himself, is rather too large than the reverse; the 20’ of Pro- 
fessor P. he considers perfectly absurd. There is only one of 
Professor P.’s objections which he does not answer; he does not 
state whether he saw a and 0 Cancri at the same time or not. 
This seems to be the crucial point of the whole question, and 
it is to be hoped that Professor Watson will make a clear state- 
ment concerning it. Mr. Swift has also replied in the A.N. 
2277. He had, immediately after the eclipse, informed the 
other observers near him that he had seen two objects with 
sensible (though he acknowledges, spurious) discs about 3° S.W. 
of the Sun, 12’ apart. Later on he changed this estimate to 7’ 
or 8’ ina letter to Nature (xviii, p. 539), in which he made a 
curious mistake, putting 8’=2". Professor Peters can hardly be 
blamed for having felt suspicious at all this confusion, or for 
having made little of Mr. Swi‘t’s comparison of the distance 
between Mizar and Alcor, with the distance between the two 
unknown objects. 
In the second part of his article Professor Peters discusses 
some of the so often quoted observations of black round spots 
passing over the Sun, nearly always made by obscure amateurs, 
SciEN, Proc., R.D.S. VOL. U., Pr, vi. 2H 2 
