14 
tives were obtained on 81 days, showing sun 
spots on 18, distributed as follows : Two in 
September, two in December, five in Janu- 
ary, five in February, three in March and 
one in April. Visual observations of the 
sun in May indicate the same low state of 
solar activity. 
STANDARD CLOCK. 
Preparations are now in progress for in- 
stalling a standard clock in a hermetically 
sealed case to be kept in a double-wall 
chamber at a constant temperature. The 
device for keeping the temperature constant 
is entirely similar to that now employed so 
successfully in the temperature room for 
testing chronometers. I consider this sub- 
ject as one of the most important for the 
future of the fundamental work of the Ob- 
servatory, and no pains or expense ought 
to be spared in securing the best possible 
performance of a standard clock under the 
conditions above described. I regret that 
the preparations for the eclipse so com- 
pletely occupied the resources of the Ob- 
servatory that this important matter has 
had to be laid aside until the present time. 
AIMS AND METHODS OF STUDY IN 
NATURAL HISTORY.* 
I rnvite your attention to an old but still 
fruitful topic, namely, the aims and methods 
of study in natural history. It is a well- 
worn theme, but one that will retain its 
interest to the naturalist 80 long as natural 
history remains a progressive subject ; and 
I venture to think that it was never more 
timely than at the present period of intense 
activity in natural science, of rapid devel- 
opment of new aims and methods, and of 
continually shifting point of view. How 
great the changes have been in the last 
* Presidential Address delivered at the annual din- 
ner of the American Society of Naturalists, Balti- 
more, December 28, 1900. 
SCIENCE. 
[N.S. Vou. XIII. No. 314. 
twenty or even ten years is, I dare Bay, 
hardly realized by many of the younger 
generation of naturalists to-day. To appre- 
ciate their full extent one must be old 
enough to have passed his student days in 
the sixties and seventies, at a time when it 
was still possible to discuss the truth or 
error of the evolution theory; when the germ 
theory of disease was itself no more than a 
germ ; when a gastrula or a karyokinetic 
figure was a thing to be spoken of with 
bated breath, but not to be looked upon 
when there were no oil-immersion-lenses 
or Abbe illuminators, no automatic micro- 
tomes, no ribbon-sections, no chromosomes 
or centrosomes, no shaking of eggs, no 
‘taxes’ or ‘tropisms’; when to adopt the 
career of a. naturalist was to face the immi- 
nent prospect of extinction in the struggle 
with the environment, and to incur the half- 
admiring, half-contemptuous compassion of 
one’s relatives and friends. 
Speaking as I am in the presence of some 
of those who guided my own first tottering 
footsteps along the pathway of science, 
I feel some hesitancy in claiming a place 
among those veterans of the old guard ; but 
I am nevertheless able to recall days when 
we had to do without all the things I have 
mentioned, as well as a good many others, 
both material and spiritual, that are now 
considered the very bread of life in the day’s 
work. I will confess, too, that I am old 
enough to be at times lost in wonder at the 
child-like serenity with which the modern 
student will accept many of these matters, 
which cost such travail of the spirit, and at 
the distant epoch to which I have referred 
would have produced a sensation through- 
out the scientific world. When, for instance, 
Kleinenberg made the famous declaration 
‘Es gibt gar kein mittleres Keimblatt’ it 
seemed to us that the sky must fall on such 
a blasphemy. We have changed all that. 
Cite those memorable words to-day, at the 
climax of your cautious discussion of the 
