568 Chronicles of Science. — [Oct., 
M. Otto Struve, after accumulating a large number of double- 
star measures, became aware of this tendency to error; and to 
determine its amount and law instituted a series of measures of 
artificial double stars, set up at a distance from the Pulkova 
Observatory, and observed with the great equatorial. ‘The results 
of such observations are of course very valuable, but the plan is 
clearly not one that can be generally adopted. It becomes. impor- 
tant, therefore, to consider whether the objections raised by Struve 
to the use of the prism proposed by Mr. Dawes are well grounded. 
Mr. Dawes says, that having for thirty-five years used prisms 
made by Dollond, Merz, Simms, and Andrew Ross, he has found 
that no one of them produced sensible deterioration of the image, 
and that the loss of light is so small that very delicate objects can 
be observed with this arrangement. 
Mr. Pogson presents the results of a series of observations of 
the planet Mars, with the Madras equatorial and meridian circle. 
It will be remembered that Major Tennant, Government Astro- 
nomer at Madras in 1860, declined (prudently in Mr. Pogson’s 
opinion) to undertake a similar series of observations. The object 
Mr. Pogson proposed to himself was rather the illustration of the 
method proposed by Mr. Airy (eight or nine years ago), for the 
correction of the constant of solar parallax, than the realization of 
any trustworthy result. 
One hundred and fourteen observations were made with twenty 
comparison stars, between September 22 and October 28, 1862. 
Owing to the many imperfections of the Madras equatorial, and 
the low magnifying power employed (63 only), the result was not 
so satisfactory as Mr. Pogson could have wished, but we think few 
will agree with him in viewing it as devoid of “any actual value.” 
It affords high evidence of the value of the method proposed by 
Mr. Airy, and confirms, as far as it goes, the opinion that the 
long-adopted value (Bessel’s) of the parallax requires to be con- 
siderably increased. Mr. Pogson’s observations give 9”°156 as 
the value of the solar parallax. It will be remembered that 
Hansen, Stone, Leverrier, and Winnecke give, respectively, the 
values 8-916, 8’°943, 8”-950, and 8”:964. Pogson’s value 
differs much less from the mean of these values in excess than 
Bessel’s (8 °578) in defect. It is noteworthy that Stone’s value is 
exactly equal to the mean of the four values just named. Adding 
the two other less trustworthy values, we obtain a mean almost 
exactly equal to Hansen’s. 
Mr. Waterston discusses the effects of such a sudden increase of 
the sun’s mass as (in the opinion of many astronomers) seems to 
be indicated by the sudden blaze of ght observed by Messrs. Car- 
rineton and Hodgson on September Ist, 1859. He deals first 
with the opinion some have expressed that the absolute increase of 
