April 12, 1883] 
acquaint themselves with the improvements continually 
made in this branch of their science. This could best be 
done by the establishment at convenient places of collec- 
tions designed to exhibit the progress of photography as 
applied to astronomical observations. 
The Harvard College Observatory has some special 
advantages for forming such a collection, since it already 
possesses many of the early and historically important 
specimens which would naturally form part of the series. 
Among these may be mentioned four series of daguerreo- 
types and photographs of various celestial objects taken 
at this Observatory. These series were respectively under- 
taken in 1850, 1857, 1869, and 1882. 
At present, the astronomers of the United States have 
no ready means of comparing their own photographic 
work with that done in Europe, or even with that of their 
own countrymen. The proposed collection of photo- 
graphs, so far as it could be rendered co nplete, would 
greatly reduce the difficulty. 
It is therefore desired to form, at the Harvard College 
Observatory, a collection of all photographs of the 
heavenly bodies and of their spectra which can be ob- 
tained for the purpose; and it is hoped that both European 
and American astronomers will contribute specimens to 
this collection. Original negatives would be particularly 
valuable. It may happen that some such negatives, 
having slight imperfections which would limit their value 
for purposes of engraving, could be spared for a collection, 
and would be as important (considered as astronomical 
observations) as others photographically more perfect. 
In some cases, astronomers may be willing to deposit 
negatives taken for a special purpose, and no longer 
required for study, in a collection where they would retain 
a permanent value as parts of an historical series. Where 
photography is regularly employed in a continuous series 
of observations, it is obvious that specimen negatives only 
can be spared for a collection. But in such cases it is 
hoped that <ome duplicates may be available, and that 
occasional negatives may hereafter be taken for the pur- 
pose of being added to the collection, to exhibit-recent 
improvements or striking phenomena. 
When negatives cannot be furnished, glass positives, 
taken if possible by direct printing, would be very useful. 
If these also are not procurable, photographic prints or 
engravings would be desirable. 
In connection with the photographs themselves, copies 
of memoirs or communications relating to the specimens 
sent, or to the general subject of astronomical photo- 
graphy, would form an interesting supplement to the 
collection. A part of the contemplated scheme will in- 
volve the preparation of a complete bibliography of the 
subject, including a list of unpublished photographs not 
hitherto mentioned in works to which reference may be 
made. 
The expense which may be incurred by contributors to 
the collection in the preparation and transmission of 
specimens will be gladly repaid by the Harvard College 
Observatory when desired. 
EDWARD C. PICKERING, 
Director of the Harvard College 
Observatory 
Cambridge, Mass., February 21 
DARWIN AND COPERNICUS * 
HE losses by death which natural science has sus- 
tained during the past year are unusually heavy. 
The fertile and ingenious mathematician who for more 
than a generation held a leading position among French 
men of science as the publisher of one of the best-known 
mathematical journals ; the chemist who, by the first 
organic synthesis, helped to dispel the illusion of vital 
t Address by Prof. E. Du Bois Reymond at the anniversary meeting of 
the Berlin Academy of Sciences. 
NATURE 
537 
energy ; the physiologist who solved one of the oldest 
problems of humanity—are men whose death leaves a void 
not easily filled up. But the lustre of even such names as 
Liouville, Wéhler, and Bischoff pales before that of the 
first on our list, Charles Darwin. Nearly every learned 
Society in existence has publicly deplored his loss. As 
this Academy has not hitherto found a fitting opportunity 
for doing so, it is necessary to add a few words to the 
formal mention of his decease, to show that we also 
appreciate the greatness of the man and of the loss 
science has sustained in him, 
To say anything fresh concerning him will only be 
possible when the lapse of time and the progress of 
science have opened up new points of view; and the 
speaker, who has often had occasion to discuss Darwin 
before this Academy, finds it especially difficult not to 
repeat himself, the more so as opinions of his work are 
still somewhat apt to be influenced by personal feeling. 
Darwin seems to me to be the Copernicus of the organic 
world. In the sixteenth century Copernicus put an end 
to the anthropocentric theory by doing away with the 
Ptolemaic spheres and bringing our earth down to the 
rank of an insignificant planet. At the same time he 
proved the non-existence of the so-called empyrean, the 
supposed abode of the heavenly hosts, beyond the 
seventh sphere, although Giordano Bruno was the first 
who actually drew the inference. 
Man, however, still stood apart from the rest of ani- 
mated beings—not at the top of the scale, his proper 
place, but quite away, as a being absolutely incommensur- 
able with them. One hundred years later Descartes still 
held that man alone had a soul and that beasts were mere 
automata. Notwithstanding all the labour of naturalists 
since the days of Linnzeus, notwithstanding the resurrection 
of vanished genera and species by Cuvier, the theory of 
the origin and interdependence of living things, which 
was almost universal five-and-twenty years ago, was only 
equalled in arbitrariness, artificiality,and absurdity by the 
celebrated theory of Epicycles, which caused Alfonso of 
Castile to exclaim, “If God had asked my advice when 
he created the world, I should have managed things much 
better.” 
“Afflavit Darwinius et dissipata est,” would, alluding 
to the above-mentioned theory, be a fitting inscription 
for a medal in honour of the “ Origin of Species.’’ For 
now all things were seen to be due to the quiet develop- 
ment of a few simple germs ; graduated days of creation 
gave place to one day on which matter in motion was 
created; and organic suitability was replaced by a 
mechanical process, for as such we may look on natural 
selection, and now for the first time man took his proper 
place at the head of his brethren. 
We may compare Copernicus’s student days at 
Bologna with Darwin’s voyage in the Aeag/e, and his 
retired life at Frauenburg with Darwin’s in his Kentish 
home, up to the time when the appearance of Mr. 
Wallace’s work caused him to break his long silence. 
Here happily for Darwin the parallel ends. Many 
circumstances combined in Darwin’s case to render his 
task easier and insure his ultimate triumph. Botany 
and zoology, morphology, the theory of evolution, and 
the study of the geographical] distribution of plants and 
animals, had advanced far enough to allow of general 
conclusions being drawn from them; Lyell’s sound 
sense had freed geology from the hypotheses which dis- 
figured it, and introduced the idea of uniformity into 
science. The doctrine of the conservation of energy had 
been put on a new basis, and extended so that in combi- 
nation with astronomical observation it gave rise to 
entirely new views of the history and duration of the 
universe. The doctrine of vital energy had been proved 
to be untenable on closer investigation. An unusually 
dry season had some years earlier led to the discovery of 
, the so-called lake-dwellings in the bed of one of the 
