NALORE 
141 

THURSDAY, APRIL 8, iors. 

THE COMPLETE WORKS OF TYCHO 
BRAHE. 
Tychonis Brahe Dani Opera Omma. _ Edidit 
IL Es Dreyer. | fomus 1) Rps lix-e320. 
(Copenhagen: Gyldendalske Boghandel Nordisk 
Forlag, 1913.) 
ERHAPS one’s first sensation on handling 
this beautiful volume is one of surprise 
that three centuries have been allowed to pass 
after Tycho’s death before his writings were given 
to the world in a collected form; for he took a 
notable part in building the structure of modern 
astronomy. He was the first to realise the imper- 
fections of the existing solar and planetary tables, 
and the fact that their improvement needed pro- 
_longed observations with larger and more care- 
fully designed instruments than any that had yet 
been employed; he fortunately had the skill to 
design these, and the means to purchase them. 
Thanks to the bounty of Frederick II., he was 
enabled to found Uraniborg Observatory, where 
sun, moon, planets, and stars were observed 
assiduously for twenty years. 
The planetary observations led Kepler to the 
enunciation of his three laws, those of the moon 
led Tycho himself to detect the variation and 
annual equation, also the oscillatory changes of 
the node and inclination; those of the sun led to | 
the detection of atmospheric refraction, and an 
approximate measure of its amount. Those of 
comets showed, by the minuteness of their diurnal 
parallax, that they were much more remote than 
the moon, and hence that they were not vapours 
in Our own atmosphere, as many had supposed, 
but belonged to the planetary sphere. His obser- 
_ vations of the fixed stars were far more precise 
than any previous ones, so that according to Dr. 
Dreyer the probable error of his standard right 
ascensions is only 24”; thus we may reasonably 
conjecture that if Tycho had lived a few years 
later, and known of the telescopic method, his 
results might be of utility even in our day. 
The present reprint is under the auspices of 
“Det Danske Spreg og Litteratur Selskab,” which 
has been fortunate in securing the services of 
Dr. Dreyer as editor. The task is evidently a 
labour of love with him, as he has made a special 
study of Tycho’s life, having written his biography 
in 1890; he has written a Latin preface of fifty- 
nine pages in the present work, giving a bio- 
graphical outline and a summary of the astro- 
nomical achievements; the fuller biography should 
however, be read by all serious students of his life. 
Mr. G. A. Hagemann is generously bearing the 
NO. 2371, VOL. 95| 

cost of the publication of the collected works, 
which must be considerable, as it is being carried 
out in a sumptuous manner, with very large, clear 
type on thick, strong paper, and will run into 
several volumes. 
The heavens themselves signalised in a brilliant 
manner the advent of Tycho by the outburst of 
Nova Cassiopeiae in 1572. The memoir, “De 
Nova Stella,” the first of his published 
writings, and appropriately begins the collection. 
“Last year, on the evening of November 11, while 
contemplating the stars, according to my custom, 
I observed a new, remarkably bright one nearly 
overhead. And since from my boyhood all the 
stars were perfectly familiar to me (such know- 
ledge is not difficult to acquire) it was certain that 
there had not been even a faint one in that posi- 
tion, much less one of surpassing splendour.” 
Mistrusting his own eyes, he quickly got his 
neighbours to verify the discovery, which appeared 
more startling to him than to us, since he knew 
of no parallel except the star of Hipparchus. 
He diligently observed the position of the Nova 
at various hour-angles, and after some months’ 
observation satisfied himself that it had neither 
proper motion nor diurnal parallax (on his geo- 
centric hypothesis annual parallax was not to be 
expected), so he rightly concluded that it belonged 
to the sphere of the fixed stars; the fact that it 
scintillated confirmed this view. He estimated its 
bulk as many hundred times that of the earth, 
no doubt thinking himself very daring. 
His notes on the magnitude and colour are 
interesting, to compare with those on modern 
Nove. In November, 1572, the Nova was much 
brighter than Venus, so that many people saw it 
in full daylight; at that time its colour was com- 
pared to that of Jupiter. The brightness in 
December was equal to Jupiter, in February and 
March to a star of the first magnitude, in May to 
one of the second. The colour became red like 
Mars or Aldebaran; later still it became livid like 
Saturn. 
The astrological significance of the Nova is 
fully discussed; Tycho made some lucky hits; in 
the.next century many people saw in the career 
of Gustavus Adolphus a striking fulfilment of the 
horoscope based on the Nova. 
The volume before us also contains the horo- 
scopes of the three sons of Frederick II. : 
Christian, Ulrich, and Hans. Dr. Dreyer notes 
that astrology cannot be omitted if we desire to 
enter fully into the thought of that age, and that 
Tycho could not refuse to draw up these horo- 
scopes when the king, his patron, requested him 
to do so. Also, belief in planetary influence seems 
less unreasonable in the case of those who accept 
G 
Was 
