C 53 ] 
VII. On the parallax of a Lyra. By John Pond, Esq. 
Astronomer Royal, F. R. S. 
Read November 14, 1822. 
M y former experiments with a fixed telescope upon a Cygni 
have always appeared to me so decisive, as to render hopeless 
any farther attempt to discover its parallax ; but respecting 
that of a Lyras, my observations with the mural circle were 
not equally satisfactory ; for among the observations of this 
star we may find occasional discordances that admit of being 
interpreted in favour of parallax. And although I have been 
inclined myself to attribute these irregularities to other causes, 
yet their existence made it desirable to institute new experi- 
ments. The method with a fixed telescope, which I had 
contrived for a Cygni, could not here, I found, be applied suc- 
cessfully ; there being no star of nearly the same altitude but 
opposite in right ascension sufficiently bright to be observed 
throughout the year, a circumstance quite essential to that 
mode of observation. I have employed therefore the mural 
circle to investigate, 1st, the difference of parallax between 
y Draconis and a Lyras : 2dly, the absolute parallax of the 
latter star ; the Dublin observations indicating, it may be 
remembered, that the parallax of y Draconis is insensible, 
but that of a Lyras a very perceptible quantity. The pro- 
cesses employed in these two investigations being very dif- 
ferent, I shall consider each of them separately. 
