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accurate results ignored. Thus, on page 261 we find Schroter (Epoch, 1780- 
1810) quoted as the authority as to the density and refraction of the 
atmosphere of Venus, whilst the author ignores the only trustworthy 
results, those of Madler (1840-1850), and Lyman (1865-1875), though they 
prove Schroter’s results to he erroneous. Again, the author (pages 183 and 
290) quotes and makes use of the value of the solar parallax derived from the 
transit of Venus of 1874, and published in the Report of the Astronomer 
Royal, ordered to be printed by the House of Commons, July 6, 1877, 
though it is well known that this result is valueless. It has, in fact, 
been practically abandoned even by its author. No reference whatever is 
made to the later results obtained by Major Tupman, nor to that found by Mr. 
Stone. In the last chapter, headed ‘ Astronomical Constants,’ and 
occupying some ninety pages, there are innumerable cases of this inex- 
perience as to what are trustworthy results and what are valueless, though 
accuracy in these data is of the most enormous importance to students. 
Time after time we find a long list of old results quoted — results a few of which 
may possess a little interest as curiosities, though of no value to Astronomy, 
whilst many of the most important modern determinations, often in fact 
the very determination in general use, are completely ignored. Thus for 
the obliquity of the ecliptic the only two modern values are Leverrier and 
Airy, and for Precession, Struve and Leverrier ; Nutation and Aberration 
fare better. In the solar parallax we have Encke’s earlier result only ; 
Leverrier’s early result, given as derived from ‘ the parallactic equation of 
the Moon:’ Hansen’s earlier and erroneous value only, and Tupman and 
Stone from the transit of Venus; and Downing and Hall from the observation 
of Mars completely ignored. Eor the planets we have Leverrier’s elements 
given, but mostly with wrong epochs. The diameters without Young’s 
value for Mercury ; Plummer, Hartwig, and Auwers, for Venus; Ellery, 
Encke, Galle, Pritchett, for Mars, &c. For the value of the secular 
acceleration in the motion of the Moon we do not find either Adams or 
Delaunay’s latest theoretical values, nor Hansen’s last value from observa- 
tion ; but we do find Airy’s last value, now admitted by its author to be 
erroneous, and one which was generally known to be erroneous from the 
very day it was published. In the values for the lunar parallax we find no 
reference to Adams, Breen, or Hansen. For the semidiameter the only 
modern value is that from the eclipses of 1860 and 1870, and all unnoticed are 
Burckhardt’s, Plana’s, Pierce’s, Hansen’s, and the Greenwich values. Under 
the head of the Lunar Equator we find either the lunar crater Manilius 
treated as an observer of the Moon, or the lunar observer Nicollet treated 
as a lunar crater, or perhaps both ; and the results which Nicollet deduced 
from observations of the spot Manilius made by the astronomers, Arago, 
Bouvard, and Nicollet, are assigned first to Poisson and then to Plana. The 
section on the figure of the Moon is in helpless confusion, and hopelessly 
wrong. In the section on the Topography of the Moon, we find no 
reference to either Lohrmann’s important map or his sections ; and even 
Beer and Madler’s Der Mond is omitted, whilst Sir W. Herschel’s ‘ Astro- 
nomical Observations relating to the Mountains of the Moon ’ is carefully 
inserted. This list must be enough, and yet we have only run lightly over 
a third part of the ninety pages of this chapter. 
